See also:

Priority options
The driver has priority The source selected via iDrive in the front is output on the vehicle loudspeakers and can be selected but not operated from the rear. Other audio or video sources ...

Adjusting
Vehicle Equipment ...

Operational readiness of airbag system
Operational readiness of airbag system In the radio ready state and beyond the warning lamp comes on briefly to indicate that the entire airbag system and the belt tensioners are operational. ...