You can protect PDF documents against unauthorized access or modification by specifying password security schemes for them. These can be stored in your system.
To apply a scheme to a PDF document or create a new one, click the Security tool in the Panel bar:
If you do not see this tool, right-click in an empty area of the Panel bar and select it.
For details, see Security Panel. You can also use the Security ribbon.
Password security schemes may include the following types of passwords.
Open Password: If specified, all subsequent document readers are asked to enter it in order to view the document.
Permissions Password: If specified, any document reader must enter it in order to modify document permission settings for printing, modifying, commenting, copying, etc.
For details, see the Password Security dialog box.