Yaw does not stop when rudder input stops

I have a QAV 540G with pixhawk and have been flying mostly LOS to dial it in. It has one issue that I don’t seen to be making any headway on. I preformed the auto tune procedure a couple of times and that works great to get you flying. It is pretty stable after doing that, the problem is that it does not hold yaw. What I mean is that if you use rudder to yaw, after you bring the rudder stick back to center the quad yaws in the opposite direction and then stops. I have even noticed in straight flight it seems to yaw a little left and right. Though it is not fast if you punch up and down when in alt hold or loiter it does seem to hold the yaw then? So it really is noticeable when using rudder commands. I have tried adjusting the YAW PIDs one at a time and then test. None of my adjustments made any change with rudder stick adjustments but would affect yaw in the punch out tests. Any ideas you to fix this as it is noticeable when I shoot video.