I have a 2018 SL450. The manual for this seems to be non-existent. I have a remote on the steering wheel, on the transom, and on the passenger side. The remote on the passenger side has the main volume control (+ and -) and them (4) separate volume controls (+ and -). Should I assume the separate controls are for the different "zones"... cabin, tower, bow, and subs? I am having trouble dialing it in. If anyone has any knowledge of this I would appreciate the help. Also if anyone knows of a manual for this remote in particular that would be greatly appreciated.

Thanks,