MacOS Big Sur - How to completely change admin password (including sudo commands)
Solution 1:
Using the system preference pane is the best way to change password since that will update associated keychain and FileVault items as needed. Other methods can cause keychain to fall out of sync.
- https://support.apple.com/guide/mac-help/change-the-login-password-on-mac-mchlp1550/mac
If you open help on macOS and search for change password, you should end up with the appropriate steps if online help isn’t handy for you.