I just purchased a pre-owned 2008 A4. I can not figure out how to erase the previous owners pre-set Satellite radio settings that the "Thumb Wheel" operates on the steering wheel. I have been all over the owners manual, and can not find any info on it. I have pre-set all the stations on the radio, but the the thumb wheel does not switch to them. Any help from anyone would be greatly appreciated. Thanks.