Change your Mac startup disk
You can start up your Mac from a network volume, a different disk, or another operating system. To do so, you need to change your startup disk.
Important: If you have a Mac with an Apple T2 Security Chip, added security features may need to be set in order to change the startup disk. See What is the Startup Security Utility?
Change your startup disk once
Shut down your Mac, then do one of the following:
On a Mac with Apple silicon: Press and hold the power button until “Loading startup options” appears.
If you’re using a Mac mini, wait for the system indicator light to turn amber.
On other Mac computers: Press and hold the Option key as you press the power button to start up your Mac.
When you see the available startup disks, select one, then click the Continue button (on a Mac with Apple silicon) or the Up arrow (on other Mac computers).
The next time you restart your computer, it starts up from the disk you selected.
Set a default startup disk
On your Mac, choose Apple menu > System Settings, click General in the sidebar, then click Startup Disk on the right. (You may need to scroll down.)
Click the icon of the disk you want to use, then click Restart.
WARNING: When selecting a network startup volume, make sure you select a network startup volume and not a network install image. Selecting a network install image reinstalls your system software and may erase the contents of your disk. A standard network volume icon appears as a globe with a folder. A network install icon appears as a globe with a downward-pointing green arrow.