I had the same problem when I got mine and I asked the same question. To fix this problem reset all the trims on the Transmitter to normal. Then turn your "GAIN" all the way to the left and then turn it to the right about 1/4 turn. For the Proportion gain turn that all the way to the left and then turn it out about 1/2 way. Start from there and if it still moves alittle to the left just make minor adjustments by turning the proportion gain the the left. If it moves to the right then adjust the Proportion gain to the right.

Which ever way the heli's tail is moving, is the same way you want to adjust the proportion gain on the heli. But remember to make only minor adjustments at a time. Also, once you make the adjustments remember to unplug the battery and plug it back in so it will re-calabrate. The GAIN controll on the 4-In-1 is to help with the tail shaking and the proportion gain helps with making the tail not move to the left or right. I hope this helps. It did for me and now my heli is rock solid. Happy flying. Joe