Mercedes-Benz GLS 2020 Operator's Manual page 311

Switching the sound on/off
On the multifunction steering wheel
On the multimedia system
To mute: press volume control 1.
#
The 8 symbol appears in the status line
of the media display.
You will also hear traffic announcements and
navigation announcements even when the
sound is muted.
MBUX multimedia system 309
To switch on: turn volume control
#
change the media source.
Adjusting the volume
Adjusting with the control knob
On the multifunction steering wheel
1 or