There was an earlier question from another person that was having trouble because of protected view. Here is the answer that was posted to that question:
When you are in protected view mode in Office (which you are by default), the files you receive will be read only. To edit these files, you can turn off protected view by Opening an Office program like Word, then go to FILE>OPTIONS>TRUST CENTER>TRUST CENTER SETTINGS. Click on “protected view” then uncheck the option to “enable protected view for outlook attachments.” After you change that setting, you should be able to edit files at will.