Open a password-protected presentation, then do one of the following:
Change a password: Choose File > Change Password (from the File menu at the top of your screen). Enter the requested information, then click Change Password.
A presentation can have only one password, so if you change the password when you share the presentation, that becomes the presentation’s only password.
Remove a password: Choose File > Change Password. Type the old password, then click Remove Password.
People you invite to on you Mac.
Double-click the password-protected presentation, then place your finger on Touch ID.
If you add a password to a presentation, or change an existing password, the password applies only to the version where the password was added or changed and to subsequent versions.
If the presentation is shared, to prevent others from restoring an unprotected version of the presentation or a version with an older password, Collaborate on a shared presentation in Keynote on Mac