Press “programs and routing” and hold it for like 2 seconds and system menu will show up
Make sure global is highlighted and use the “select” turning knob and turn until you’re on the screen that shows global – pedal ctl
Turn parameter until you see “tuner”
turn ctl source and set it with the appropriate sw 1, sw 2 etc.. which ever one your aux switch is in.
However if you haven’t, it made be good idea to go to system again and I/O section and use “select” knob and scroll until you see exp & aux and set up your exp or aux stuff there and calibrate if needed.