Hit the right knob to get the bass/treble/fader/bal option.
Once selected cannot go left and right on the little graphic. And of course the adjustment is tracking the display.

Range of adjustment is limited to center to right. Click click it again and sometimes it will let me adjust left to center but in either case cannot go both ways left of and right of the center mark on the lcd display.

Been that way since I got it but was hoping it would correct itself.
Warranty time I guess.