Modifying this control will update this page automatically
macOS User Guide
- Welcome
-
- Change System Preferences
- Change your desktop picture
- Add your email and other accounts
- Use a screen saver
- Change the picture for you or others in apps
- Set up other users on your Mac
- Set up Screen Time for yourself
- Change the system language
- Make it easier to see what’s on the screen
- Use accessibility features
- Run Windows on your Mac
-
- Use Continuity across your devices
- Stream audio and video with AirPlay
- Use your iPad as a second display
- Hand off between devices
- Insert photos and documents from iPhone or iPad
- Insert sketches from iPhone or iPad
- Copy and paste between devices
- Use Apple Watch to unlock your Mac
- Make and receive phone calls on your Mac
- Control accessories in your home
- Send files between devices with AirDrop
- Use AirPods with your Mac
-
- Manage cookies and other website data in Safari
- Use Private Browsing in Safari
- View privacy reports in Safari
- Understand passwords
- Reset your Mac login password
- Use keychains to store passwords
- Set up your Mac to be secure
- Guard your privacy
- Use Sign in with Apple for apps and websites
- Protect your Mac from malware
- Control access to your camera
- Find a missing device
- Resources for your Mac
- Resources for your Apple devices
- Copyright
If the identity of a backup disk has changed on Mac
For security, Time Machine won’t do a backup if it detects that the identity of your backup disk has changed. This can happen for several reasons:
You erased or reformatted your backup disk or partition.
You deleted the disk image for your backup disk.
You connected another disk to your Mac with the same name as your backup disk.
Someone is trying to steal your information by tricking your Mac into backing up to an unauthorised disk.
If you connect another disk to your Mac, give it a different name from your backup disk. Then make sure your backup disk is correctly identified. On your Mac, choose Apple menu > System Preferences, click Time Machine, then reselect your backup disk.
Thanks for your feedback.