Uconnect 8.4 NAV Supplemental Owner's Manual page 118

UCONNECT 8.4A/8.4AN 117
Press the "AUX Volume Offset" button on the touch-
screen to activate the AUX Volume Offset screen.
The AUX Volume Offset is adjusted by pressing of the
"+" and "–" buttons. This alters the AUX input audio
volume. The level value, which spans between ±3, is
displayed above the adjustment bar.
Surround Sound
4
Press the "On" button on the touchscreen to activate
Surround Sound. Press "Off" to deactivate this feature.
When Surround Sound is On, you can hear audio coming
from every direction as in a movie theatre or home
theatre system.