Fiat 500X Owner's Handbook Manual page 234

CONTROLS BEHIND THE STEERING WHEEL
Buttons
Button A (left side, behind the steering wheel)
Upper button
Central button
Lower button
Button B (right side, behind the steering wheel)
Upper button
Central button
Lower button
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Interaction
Brief button press : search for next radio station or selection of USB next track.
Long button press : scan of higher frequencies until released/fast forward of USB track.
With each press it scrolls through sources AM, FM, DAB and USB. Only the available
sources will be selected.
Brief button press : search for next radio station or select USB previous track
Long button press : scan of lower frequencies until released/fast forward of USB track.
Increasing volume
Brief button press : single volume increase
Long button press : fast volume increase
Activation/deactivation of Mute function
Decreasing volume
Brief button press : single volume decrease
Long button press : fast volume decrease