I have a Voyager, but don't believe the knobs are the same as yours. One knob on each side, a lever for manual braking and a single multicolor LED.
The left knob is to level the sensor and the right knob is gain. No input signal control crossover type function as far as I know.
Once it is installed, you should only have to play with the gain based on load and brake performance.
If the trailer brakes lock up or the trailer feels like it brakes first and pulls the truck back, gain is to high.
If it feels like the trailer is pushing the truck under braking, turn up the gain.
I make a couple test slows/stops every time I drive it. I've even been known to turn up the gain when empty to make sure both sides chirp/lock evenly.
