You can assign a password to a document so that only those who know the password can open the document. Passwords can consist of almost any combination of numerals, capital or lowercase letters, and special keyboard characters.
A document can have only one password. If you change an existing password when you share a document with others, the new password replaces the original.
Important: There’s no way to recover your password if you forget it. Be sure to choose a password you won’t forget, or write the password down in a safe place.
If your computer or iOS device has Touch ID, you can use it to open documents with your fingerprint alone.
Tap 
, tap Set Password, enter the requested information, then tap Done.
When you open a password-protected document, you can turn on “Remember this password” so you don’t have to type the password each time.
If you add a password after you share a document, be sure to notify participants.
Note: Adding a password to a document encrypts the file.
With the document open, do one of the following:
Change a password: Tap , then tap Change Password. Enter the required information, then tap Done.
A document can have only one password, so if you change the password when you share the document, that becomes the document’s only password.
Remove a password: Tap , tap Change Password, then turn off Require Password. Type the old password, then tap Done.
If your iOS device has Touch ID, you can open your password-protected documents using your fingerprint.
To set up Touch ID for opening password-protected documents, do both of the following:
Set up Touch ID for your device: On the Home screen, tap Settings, tap Touch ID & Passcode, then enter your passcode. Tap “Add a fingerprint,” then follow the onscreen instructions.
Note: If you don’t see Touch ID & Passcode, this feature isn’t available on your device.
Set up Touch ID for Pages: On the Home screen, tap Settings, tap Pages, then turn on Use Touch ID.
Tap the document, then place your finger on the Home button.
Note: After you set up Touch ID, you can use either your fingerprint or the password to open a protected document.
If you add a password to a document, or change an existing password, it applies only to that version of the document and to subsequent versions.
If the document is shared, to prevent others from restoring an unprotected version of the document or a version with an older password, stop sharing the document, add a unique password to it, then share the document again.