You must make a small adjustment on the clevis on the elevator. You need to put a little down elevator into the plane. Rotate the clevis on the end of the rod about 10 turns counter clockwise. Fly it there, it may need more. Most of the nexstars need to have this done, I don't know if its just an adjustment or the wing generates allot of lift. IF you fly where there is a bunch of wind, 15 mph+, take the speed brakes off and the anti stall wing tips. If you remove those, you may need to re-adjust the clevis again.

You do not need to add weight or rebalance the plane, those people doing that have no idea what they are doing.

If you have an instructor, disconnect that auto pilot thing. If you are by yourself (not recomended) let it be.