VTOL drifts during Trasition from MC to FW

i changed transition class so the plane will lift up before going forward and it does it but from some reason it dosent keep its x y position,
can anybody give an advice?

What do you mean with not keeping x,y position? Starting a transition to FW will obviously make it change position. Sideways drift is something often seen, especially when doing it in windy conditions.
I think it would be best if you could share a log file (Flight Log Analysis | PX4 User Guide) of your flight.