As far as I know, the "User" column of the file history listing in any particular model file is showing the Username used for your account on whatever network you are using. You can't change this, usually, because it's tied to your credentials for network access, etc.
I don't understand why this would be a problem. Usernames used to access accounts are necessarily unique. Thus, it's easy to use them to verify who is doing things to a particular file. Maybe there's a misunderstanding about what is being required.
