sometimes by others in order to protect the use of a document, you need to encrypt PDF documents to restrict printing, copying and other operations, only for others to read, then we need to be encrypted PDF documents and so on to deal with, and now introduced to the PDF using Adobe Acrobat increased restrictions on passwords, such as restrictions on operation of print copy.

1, first of all, open Adobe Acrobat 9 software, need to be addressed to open PDF, choose "File" - "Properties" - "security" in the "security approach" in setting, the following chart:

2, in the Password Security Settings to add a password, set up to copy, print, such as restrictions on operations, the following chart:

3, all the way to confirm, and finally click on the "detailed settings" is not satisfied with a look at the settings, the following chart:

4, all set up OK after the preservation of documents.