Password Protect
a
File
You can Protect your document with a password. A
strong password includes letters and numbers. It should not be your
name.
Try it: Encrypt the Document
Go to File ->Info ->Protect Document.
Select
Encrypt with a Password.
Type a Password.
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Security is a genuine concern. Hence, there is no
"Undo" if you forget the password. Neither is there a tool that will
let you remove the encryption.
Please write down your passwords!