when you sign in with a user name and password to use a tv channel app does it affect your bill? do you have to pay extra to do that?
It appears you are speaking of smart device apps like ABC or FoxNow etc. If the app shows it accepts credentials from Xfinity then you can log in to get access. There is no charge to use the app, but you may incur internet usage costs if you are using your home account or Xfinity WIFI hotspots.