Thank you for your reply 
Yes, I read about that in the forums, but I have a big question and concern! If I upgrade the firmware, will I need to tune the copter again or recalibrate sensors such as Accelerometer/Gyroscope or Compass? Tuning is difficult for me and takes a lot of my time. For this reason, I haven’t updated it yet! If tuning is not needed, I can consider trying this upgrade.
Regarding this question, I saw it in your topics! However, I don’t understand how this GUI can help me.
My question, which I suspect has been forgotten and not answered, is: what is the ATC_SLEW_YAW parameter? Is it the PID gain for yaw? Is it harmful or dangerous to change?