Reset audio 20 radio with garmin sat nav

[mercmancdi]

Hope this is ok to ask here , 2017 glc with audio 20 garmin nav . Previous owner has all his stations set how do you do a complete retune on dab/fm.
522 AUDIO 20 RADIO NAVIGATION NTG5

 

[Botus]

on older Merc DAB tuners look on DAB for << and >> menus along the bottom of the screen. These set the car off to scan the multiplexes one by one - so might find 5 to 10 channels, then you click again and it finds another multiplex, on and on you can have 7 or so bundles of channels (the old / technical naming is a multiplex - german's call them Ensembles)