Tail servo moved so slowly

I change my yaw channel from servo4 to servo6,but when i operating with my remote control ,the servo moved slowly. How to solve this problem?

It is very common when checking the aircraft controls on the ground to see the yaw response to be slow. The servo out channel should not affect this.

Thanks for your reply but I remember that the response was very fast when I tested the tail servo before, but now it takes about 1 second to move from the neutral point to the most value point, is this normal?

Well just to be clear, you changed Motor 4 from being assigned to servo 4 to now being assigned to servo 6. If that is what you did, then there should be no change in how your tail rotor servo would respond.