Apple has increasingly made it hard to mess with macOS system files. That’s true whether you intentionally want to extend macOS’s functionality or if a malicious party is trying to install and activate a virus. However, many system components and all Apple and third-party apps rely on preferences and other files to store your custom settings, caches for work in progress, and other data. If those files corrupt, macOS may be perfectly fine, but you can’t get anything done in an app or your account.

Once you’ve gone through troubleshooting your Mac within your account that doesn’t seem to improve matters, the next big leap before reinstalling macOS is to set up a fresh macOS user account. From this account, you can test hardware, like your Wi-Fi or ethernet adapter; add printers and scanners; or run third-party software that keeps crashing on launch.

Because a fresh account typically contains nothing that would already be corrupted, you can isolate whether a problem is in your everyday user account or a system-wide issue–maybe even hardware related.

Here’s how to set up a fresh, new user account:

• Open "System Settings..." from the  Apple menu

• Go to "Users & Groups"

• Click the "Add User..." button

• Enter your password if prompted

• Choose whether to create a Standard or Administrator account, give it a name, password, and hint, and click "Create User"

When making the account, what kind should it be?

Create a Standard account if you want to test a problem from the perspective of a user without any extra privileges.

Create an Administrator if that’s your normal account type–that’s typical–and you’re trying to perform an apples-to-apples comparison.

• Choose  Apple menu > Log Out [name]

• At the login screen, select the new account, enter the password, and click the arrow to log in

Now you can check if your problem persists.

When you’ve debugged your problem, you can get rid of the account. You must be logged in using an Administrator account to do this.

A version is saved automatically every hour, or more frequently when you’re making many changes, when you open, save, duplicate, lock, rename, or revert a document. You can also explicitly save a version.

To browse, restore, duplicate, and delete versions:

1. Open the document, then choose File > Revert To > Browse All Versions.

2. Click tick marks along the timeline to browse versions.

3. Display the version you want, then do one of the following:

• Restore your document to this version: Click Restore
• Duplicate this version in a new document: Press and hold the Option key, then click Restore a Copy
• Delete this version: Move the pointer to the top of the screen to show the menu bar, then choose File > Revert To > Delete This Version
• Leave your document as is: Click Done

To revert a document to the last opened version:

Open the document, choose File > Revert To, then choose Last Opened, Last Saved, or Previous Save

To explicitly save a version:

Open the document, then choose File > Save. To save the document using a different filename, location, or format, press and hold the Option key, then choose File > Save As

Your Mac includes a built-in tool called Apple Diagnostics (formerly called Apple Hardware Test). This tool will be handy if you are dealing with a hardware issue and not a software issue. You can use it to find and diagnose issues with your Mac’s internal hardware such as the Wi-Fi hardware, the Bluetooth hardware, Touch ID, the fan, or the power adapter, etc.

Prepare your Mac

• If you can install the latest macOS updates (https://support.apple.com/en-us/108382)
• Disconnect all external devices except keyboard, mouse, display, Ethernet connection and connection to AC power
• Determine if you have an Apple silicon Mac or an Intel Mac, go to the  Apple menu > About This Mac to find out (on a Mac with Apple silicon, About This Mac shows an item labeled Chip, followed by the name of the chip, on an Intel-based Mac, About This Mac shows an item labeled Processor, followed by the name of an Intel processor)
• Shut down your Mac (if you can't shut it down normally, press and hold its power button for up to 10 seconds, until your Mac turns off - every Mac has a power button; on laptop computers that have Touch ID, press and hold the Touch ID button)
• Turn off your Mac, then wait a few seconds for your Mac to completely turn off

On an Apple silicon Mac

• Press and hold the power button on your Mac (on laptop computers that have Touch ID, press and hold Touch ID)

• As you continue to hold the power button, your Mac turns on and loads startup options

• When you see Options, release the power button

• Press and hold Command (⌘)-D on your keyboard until your Mac restarts

On an Intel Mac

• Turn on your Mac, then immediately press and hold the D key on your keyboard as your Mac starts up (if using the D key doesn't work, press and hold Option (⌥)-D at startup instead)

• Release the key when you see a progress bar or you're asked to choose a language

Run Apple Diagnostics

Follow the onscreen instructions, which vary based on your Mac, the version of macOS that it’s using, and whether certain parts of your Mac have been repaired or replaced.

As you follow the onscreen instructions:

• If your Mac isn’t already connected to the internet, you’re asked to choose a Wi-Fi network, or you can use an Ethernet cable to connect to your network

• If asked to review terms and conditions, you might be given the option to run diagnostics offline (in that case, click Run Offline)

• In macOS Tahoe 26 and later, you’re asked to choose a specific diagnostic to run, such as a diagnostic for your built-in display, keyboard, or trackpad; in earlier versions of macOS, this is automatic

When testing is complete, Apple Diagnostics shows the results. If you see one or more reference codes and need more explanation, refer to the list of Apple Diagnostics reference codes (https://support.apple.com/en-us/102334).

If you can't use this information to resolve the issue on your own, you might need service (https://getsupport.apple.com/?caller=kbase). Provide the reference code you receive from the test when taking your Mac to an Apple Authorized Service Provider, Apple Store, or an Independent Repair Provider. Genuine Apple parts are also available for out-of-warranty repairs through Self Service Repair (https://support.apple.com/self-service-repair).

Browsing history is a record of every webpage you visit. Your browser stores the URLs for every page, except when you use private browsing mode. Browsing history can help improve your browsing experience (e.g. as you start typing a URL in the address bar of your browser, previously visited URLs display in a dropdown list that match what you're typing), but it also exposes your browsing habits. If other people use your Mac from time to time, or you get family members looking over your shoulder as you surf the web, you may want to delete your browsing history on a regular basis.

You can manually clear your browsing history in Safari at any time. Two of the ways to clear all your browser history are:

• Choose "Clear History" from the Safari application menu
• Choose "Clear History" from the History menu

but be aware that the name "Clear History" is misleading. Clicking "Clear History" also deletes other website data, like cookies and the entire browser cache. However, there is a way to clear your browsing history without losing website data.

Simply choose the Safari or History menu, but press and hold down the Option key before selecting the "Clear History" option. You'll see the option change to "Clear History and Keep Website Data". Keep the Option key pressed and select that option.

• Avoid using a Mac on a bed or fabric surface. Anything soft doesn’t allow for sufficient heat dispersion and can even block the air ventilation on many portable Macs, try to always use a Mac on a hard surface of wood, metal, or glass.

• Use a laptop stand. On hot summer days a laptop stand can mean the difference between having the fans blasting or not having them on at all. Anything that raises a Mac away from a base surface allows for heat to radiate out and for air to flow around it, cooling the hardware. Some laptop stands have built-in fans that blow directly onto the underside of a computer, these can be very effective.

• Raise the rear of a MacBook. No laptop stand? Make do with what you have, and try placing the rear of the Mac elevated by a hardcover book or something similar. It’s not as effective as a laptop stand, but this promotes airflow and can make a significant difference in keeping hardware cool.

• Place a Mac at the edge of a table or desk. No stand and no book to raise the computer with? Try hovering the rear end of a MacBook over the edge of a desk or surface to increase air flow where Macs blow out their heat.

• Use a fan. Yes, a standard room fan. This may sound silly but if you’re in an environment without air conditioning, pointing a fan onto a Mac will blow cool air onto it and help disperse heat. If you’re using a Mac in temperatures over 90°F (32°C), this is one of the best things you can do to not only keep yourself cool but also your computer.

• Keep away from the sun. Again this may seem like common sense, but using a computer in direct sunlight places an unnecessary burden on the fans. Even on reasonably mild sunny days the sun can cause fans to go into overdrive, it’s best to avoid direct sunlight completely.

Finally, a quick word of advice: if you’re in extreme heat and you don’t have any method to cool down your Mac, do yourself a favor and don’t use it at all until you get out of the crazy weather. Heat is one of the most detrimental forces to anything electronic and overheating can lead directly to reduced lifespan of hardware, diminished battery capacity, and other problems. It’s always better to be safe than sorry.