Acrobat Pro (version X or later) – Securing documents with password
You can restrict access to a PDF file by setting the Document Open Password so that users have to enter a password to open the PDF file.
||You may set your password in either ways shown below:
- Open the PDF and choose Tools > Protection > Encrypt > Encrypt with Password.
- You can also choose File > Properties and select the Security tab.
||If you receive a prompt, click Yes to change the security.
||Select the type of password to add, and then enter your own password in the corresponding field.
||Click OK at the prompt to confirm each password, retype the appropriate password in the box and click OK.
Important: If you forget the password, there is no way to reset and you will never be able to access the file. Consider keeping a backup copy of the PDF that is not password-protected.