PID stting error

ArduCopter
1

I have a PID setting of 1500 hexacopter drones.

After setting the PID value obtained through autotune, the drone is stable.
Afterwards, I recalibrate the sensor and re-enter the PID value from autotune, but the drone is unstable.

I want to know why

2

Start here before running Autotune:
http://ardupilot.org/copter/docs/tuning-process-instructions.html