Answer:
If the helicopter tries to drift in a certain direction or rotates without any control stick input, you may need to adjust your trim. Move the trim sliders in the opposite direction that the helicopter is drifting. For example, if the helicopter tends to drift to the right, move the aileron trim slider a few notches to the left to counteract the the drift. Similarly, if the helicopter's nose is rotating to the left, move the rudder trim slider a few notches to the right. Adjust each trim slider as necessary so that when light on its skids, the helicopter remains as stationary as possible. Some drifting is normal because the helicopter is fighting ground effect.
If you've moved your rudder trim slider all the way to the end of its travel and the helicopter's rotation in the opposite direction is still not corrected, you may need to adjust the proportional trimmer potentiometer (pot) on the helicopter's receiver. Refer to your manual for more detailed instructions, but essentially this dial controls how fast the tail rotor spins relative to the main rotor. Turning the dial clockwise makes the tail rotor spin faster, which rotates the helicopter's nose to the right when spun up. Similarly, turning the dial counter-clockwise decreases the tail rotor speed, which rotates the nose to the left. By trial and error, adjust the trimmer pot so that when your rudder trim slider is close to its center of travel, the helicopter remains stationary