Open the PDF in Adobe Acrobat
Go to File
Select Properties
Open the Security tab
Choose a security method
Set a password for editing restrictions
Disable editing permissions
Save the PDF
Use a PDF editor with permission settings
Set the document to read-only
Restrict copying, printing, and editing
Apply a permissions password
Save the secured file
Use Microsoft Word if the PDF was created from a Word document
Open the original document
Protect the document
Export or save it as PDF
Use online PDF protection tools
Upload the PDF
Set editing restrictions
Download the locked PDF
Use operating system file permissions
Mark the file as read-only
Restrict write access for users
Save the file in a protected location