You can assign a password to a presentation so that only those who know the password can open the presentation.
Passwords can consist of almost any combination of numerals, capital or lowercase letters, and special keyboard characters.
Choose File > Set Password (from the File menu at the top of your screen), enter the requested information, then click Set Password.
Select the checkbox if you want to add the password to your keychain.
If you add a password after you share a presentation, be sure to notify collaborators.
Note: Adding a password to a presentation doesn’t encrypt the file.
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.
Remove a password: Choose File > Change Password. Type the old password, then click Remove Password.
Passwords apply to presentations when you share them using iCloud, so your collaborators need the password to open the presentation. A presentation can have only one password to open it. If you change the password when you share the presentation, that becomes the presentation’s only password.
When you add or change a password, the password applies only to versions created after the password was added or changed. To prevent others from restoring unprotected versions or versions with older passwords, stop sharing the presentation, add a password to it, then share the presentation again.
Note: You can also protect a presentation by requiring a separate password to stop or exit the presentation while it’s playing. This password requirement is useful, for example, when the presentation is set to play automatically in a kiosk.