I always use Acethinker PDF Converter to add password to protect my PDF document, it works fairly well. If you are interested in it, here are the steps about how to use it to add password. To download the app, click the âDownloadâ button below. After downloading the software, run the program and load the PDF file that you want to protect by going to âFileâ, âOpenâ, and choose the right PDF file or just drag the PDF file to Acethinkerâs main interface. From there, you can already edit your PDF file or in this case, add password protection. At the upper right corner of the screen, go to Edit Tool, âOther Toolsâ, âProtect PDFâ. Then, âchoose a fileâ to protect and it will let you add a password to your chosen PDF. After setting your password, click âOKâ to save your given password, and youâre good to go
Now let's see how Ace theorist works so that we can protect our PDF file.