Acrobat Pro DC (for PDFs)
- Open the PDF in Acrobat DC.
- Go to File, then select Protect Using Password.
- Select whether you want the password to be required for Viewing or Editing the PDF.
- Type the password you want to use twice. The password strength indicator will let you know if the password you selected is weak, medium, strong, or best.
- Select Apply. Acrobat will display a confirmation message.