Regarding Acrobat 9 pro, and I use Windows 10. I am getting an error when I try to save my document states as follows: "The document can not be saved. The file can be read only or another user have it open. Please same document with different name or folder".
Acrobat 9 is not compatible with Windows 10, so problems with it are to be expected.
You should try running it in Compatibility Mode with an earlier OS, like Windows 7.
Regarding this specific issue, make sure that the Preview panel in Windows Explorer is disabled.