How to set up encryption in PDF file?

Now a lot of files are in PDF format, some files for the company or individuals are very important, can not be disclosed, then how to ensure the security of the document? How do I encrypt it?

1, open the software into the operating interface, click on the file encryption.

2, then we can see the pop-up password input box, enter the password you remember to live a good.

3, the password after the completion of the selection of confidential methods, there is lightning encryption, according to their own needs to choose.