1. Tap Security on the sidebar.
2. Choose Set Passwords –> Open Password or set The permission to Restrict printing and copying of the document. You need to choose at least one option if you want to set the permission.
3. Tap Batch to set passwords for multiple PDF files.
4. If you want to remove one of the added PDF files, click Remove, if you want to remove all added files, click Clear.
5. After setting your passwords, click Encrypt to finish your security setting.