Mercedes-Benz A-Class Operator's Manual page 252

250 MBUX (Mercedes-Benz User Experience)
On the multimedia system
To mute: press volume control 1.
#
The 8 symbol appears in the status line
of the multimedia system display.
You will also hear traffic announcements and
navigation announcements even when the
sound is muted.
To switch on: turn volume control
#
change the media source.
Adjusting the volume
On the multifunction steering wheel
1 or
On the multimedia system
Turn volume control 1.
#
The volume of the current radio or media
source is set. The volume of other audio
sources can be adjusted separately.
Adjust the volume in the following situations:
during a traffic announcement
R
during a navigation announcement
R