How to change wifi password

I just recently upgraded my xfinity gateway. I am trying to change the password but it won't let me do it in the admin tool. It says I have to download the app, aside from being annoyed having to do this from the app the wifi section it asks you to go to does not exist in the app. The instructions say to open the app and click on wifi tab but there is no wifi tab. In fact there are no tabs at all in the android app. Do any of you know how I can get around to changing the wifi password?