There are two PDF password types - owner password and user password you can set to protect PDF files. To increase document security, you can limit access and protect PDF files by creating passwords and restricting certain features, for example, you can set owner password to prevent other people from copying, printing and modifying PDF contents. Below are some tips on how to set PDF password to protect PDF files.
1. Set password to protect PDF with Adobe Acrobat
A. Select Secure from Toolbar and click on Password Encrypt. You can also Encrypt for Certain Identities Using Certificates...
B. Set open password. Click the check box on Require a password to open the document and enter an open password if you want to restrict others from opening the PDF (users need to type the correct password before opening the document).
C. Set owner password. Click the check boxes on Permissions and enter the permissions password (or owner password, and users have to provide a right password before changing security settings). You can also set restrictions of Printing Allowed and Changes Allowed in the Permissions filed.
D. Click OK to set PDF password to protect PDF files
However, not everyone affords to this expensive office software. Actually, it's much easier to set password to protect PDF files with a simple PDF creator - Simpo PDF Creator Pro
Set PDF password to protect PDF with PDF Creator
A. Click to download the PDF Creator and install it onto your computer.
B. Add files to PDF Creator interface
C. Click Advanced Settings and Security, check the option of Enable PDF Security, uncheck the three options of Allow printing, Allow changing, Allow copy or extract to protect PDF from printing and copying. Of course, you can also give a user password to prevent other people opening your PDF. Then click OK to set PDF password to protect PDF files.