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
Determine which disk started up your Mac
Some Mac computers can be started up from a CD or DVD, a network volume, a different disk, or another operating system.
Important: If you have a Mac with an Apple T2 chip, added security features may be set to prevent the computer from starting up from an external startup disk. See What is the Startup Security Utility?
On your Mac, choose Apple menu
Click Startup Disk.
Your selected startup disk is shown at the top of the preferences pane.
See alsoChange your Mac startup disk
Thanks for your feedback.