WKM 2 not holding position

[paktazh]

Hi I just updated my WKM IMU 1 to IMU2 but when it is in GPS it does not hold postion and also when i left off if i i do it in GPS in try to flip backward it was not like that in WKM 1 which was holding postion and not tring to fli my hex copter weight is 3kg without battery with one 80006s it is 4kg any idea how to fix these problems