Why will pixhawk not let me change the altitude pid setting. I change it from 1.00 to 1.300 and click write parameter and if goes back to 1.00. I also have a drift while in stable and althold. I have re-calibrated the gps and the accel. several times and each time the pixhawk has accepted the numbers. Do you think that if I were to autotune the pixhawk it would take out the drifting? If it does not this piece of crap is going into my junk box.