I fly with my thumbs also but let the student decide what is best for them. Sounds like Bryris just needs to practice and get comfortable with what he has ( if an instructor doesn't see something wrong with his gear ). We all have had students that didn't like the way their plane was handeling, then when we check it there is nothing wrong-- just not used to the set up.
I had a student this week that kept complaning that the plane wouldn't fly straight, it always wanted to go right. I told him to let go of the controls, ( I didn't release the switch ) it flew straight as an arrow, when he started flying again it wanted to go right. Ended up HE was puting pressure to the right without knowing it. Just a matter of getting used to your equipment. ENJOY !!! RED