I presume English is not your native language. I'm having trouble understanding the issue, I presume others might have the same problem and are not chiming in to help.
If your other user has used the webGUI, then yes, they must have logged in with the "root" username/password.
I'm confused on the version numbers? You start off saying you used version 9.2.1 and then say you are using 9.2.1.7. Did you start with 9.2.1 - with everything working? And, upgrade to 9.2.1.7 and break the configuration? Or, are you both logging into the webGUI and making changes to the configuration.
Does the user access the files via Windows Explorer, using CIFS? If so, are you able to access the files via Windows Explorer with your account?