Use the PDF application's Protect or Encrypt feature, choose a strong password, and save the protected file.
Step by Step
- Make a backup copy of the original document before making major or irreversible changes.
- Use the PDF application's Protect or Encrypt feature, choose a strong password, and save the protected file.
- Review the output carefully, including page order, formatting, images, and text.
- Save the result with a new filename until you are sure it is correct.
If That Doesn't Work
- Exact menu names differ between Adobe Acrobat/Reader, Microsoft Office, browsers, macOS, Windows, and third-party applications.
- For confidential documents, avoid uploading files to an unknown online converter; use trusted software or services.