Protecting PowerPoint files from PDF conversion in Acrobat XI

  1. In the Save Adobe PDF dialog box, just make sure the “Protect PDF” box is checked:

  2. As soon as this box is checked, a dialog box pops up. Have the “Restrict editing and printing…” box checked and give it a password to keep someone from changing it:

  3. And that’s it! Here’s the error box someone gets if they try to convert this PDF in Acrobat back to Powerpoint: