Helibat was right but he had the direction to move the trim tab backwards. Under your right stick, move the trim tab to the right. I would try to or three clicks at a time until it drifts to the right and then fine tune. If it moves forward, move the trim tab that is left of your right stick down 2 or 3 clicks until it stays in place. I wouldn't move the linkage just yet until you see what happens when hovering in "clean air". (I have heard that rotor diameter X 1.5 is the height you must be at to get out of ground effect)
There is a provision on the mixer board to center your trim tab for the yaw, but not the cyclic.