In “Stabilize” mode the throttle control is too sensitive in the center and I cannot find a hovering position. In “Halt hold” and Loiter "modes it works perfectly. How can I solve this even considering I am a beginner? Thanks
You can not. That is just the way stabilize mode works.
From the documentation: “Pilot’s throttle input controls the average motor speed meaning that constant adjustment of the throttle is required to maintain altitude.” Alt Hold and Loiter explicitly try to maintain altitude, Stabilize doesn’t.
This is basically how all the freestyle quads work. With practice you get better at holding altitude.
…and very small throttle adjustments to zero in on a hover; otherwise you’ll chase it all
over the sky. Practice! GL!