Just picked up a Cert. Pre Owned 2015 A4. Can anyone tell me how to shut the radio or media off, and have it stay off? Not mute, but off. Everytime I turn on the Nav system, the radio or media comes on whatever was played last. It has become quite annoying. I've read in another thread that there is some hidden menu on the MMI where I can change the default volume to zero but the poster could not make it clear how to enter the menu. Thanks, Dave