Ok the one on the left of the controler is your rough adjust the other is to fine tune. What they do is adjust the pitch of the blades relative to the position of the throttle stick. Think of it like this in normal mode, not idle up. Your throttle adjusts the speed your motor turns, As you move the tx throttle up the motor and your blades spin faster. at the same time your moving it up you are also adding down pitch to the blades. The knobs adjust how much pitch at how much throttle. your want to get a good balance between how fast they are spinning, and how much pitch you have to get the best flight time(so your motor is working where it is most efficient, and your handleing is were you want it. Hope that isnt more confusing then what you have read already but figured I would give it a try. So to break it down. More the knob is turned up the more pitch you have and the less rpm. The lower you have them the more rpm's and the less pitch.