Xfinity RNG150N Set Top

I can't get into the RNG150N's setup menu as described in the User Guide on Pg.12.

I'd like to override the HDMI Audio setting for Dolby.

Does anybody know how to get into the General settings menu?

It's not the same as the onscreen menu that you get by pressing the "menu" botton on the Xfinity remote.

Thanks.