The top one is the LEFT/RIGHT Bias. It is used to obtain a balanced feel between left and right tail rotor inputs. The adjustment is very sensitive, so only make small changes. Turn clockwise to increase the left tail rotor bias.

The middle one is the GYRO GAIN. Turn clockwise to increase the gain. Typically too little gyro will cause he tail to slowly move around and drift. With the gyro gain too high, you will notice a very fast oscillation in the tail known as "Wag". This adjustment is not very critical so dont spend a lot of time trying to get the "best" possible setting.

The bottom one id the TAIL ROTOR TRIM. If the helicopter wants to drift one direction in a stable hover then try using this adjustment. The adjustment is very sensitive so only make small changes. Turn clockwise to add right tail rotor trim.