Hello guys,finally l learned how to calibrate escs with transmitter.But i have a problem,i have 4 escs and 4 motors and one of the motors is spinning slowly than the others.I changed the escs and it starts vibrating instead of spinning! .What should i do?

One more question,if I calibrate all the 4 motor with transmitter,and if I were to build a quadcopter,should I have to calibrate again with flightcontroller?Iam using a kk2.1.5 fightcontroller.

First thing is you dont calibrate motors but you calibrate ESC.
Depending on transmitter and flight controller, individual min and max values may be different from each other.
So it is better to calibrate esc with flight controller.

I did calibrate with motors,and i will try with flightcontroller.Thanks for the reply.