Sign into your Apple ID preferences on Mac
Use your Apple ID to sign into your Apple ID preferences. After you sign in, you can use Apple ID preferences to change your account name, photo, contact information, password and security settings, payment and delivery information and more.
If you don’t have an Apple ID account and want to create one, see Create an Apple ID.
When you sell or give away your Mac, sign out of your Apple ID to prevent others from using accounts associated with your Apple ID. See the Apple Support article What to do before you sell, give away or trade in your Mac and If you sign out of your Apple ID preferences.
Sign into your Apple ID preferences
On your Mac, choose Apple menu > System Preferences, then click Sign In.
Enter your Apple ID and password, then follow the on-screen instructions.
For information about changing your Apple ID account information on the Apple ID website, see your Apple ID account page.
Sign out of your Apple ID preferences
Sign out of your Apple ID account to prevent others from accessing your account information and Apple services on your Mac. For more information about signing out of your Apple ID, see If you sign out of your Apple ID preferences.
On your Mac, choose Apple menu > System Preferences, click Apple ID , then select Overview in the sidebar.
Click Sign Out.
Follow the on-screen instructions for copying and downloading your data stored in iCloud.