Hi! I've been in the school band for 3years now and recently, my french horn tutor (my music director hires tutors who are very good in their instruments) noticed that i have a slight overbite and he suggested that i push out my jaw so that my top row of teeth and my bottom row of teeth form a flat surface where my mouthpiece will be. But i find it very hard to play with my jaw pushed out. Will it make a very big difference if i push out my jaw and if i don't? And also, when i push out my jaw it makes it hard for me to squeeze ( i think thisnis the reason why my tutor asked me to push out my jaw ) which is good right? I tend to squeeze a lot when i play with my normal settings.

I'm actually going to graduate from my school already and i wish to join a band after i graduate,and i really want to improve and be a lot better. Do you have any method books or excercises to recommend? ╰（￣▽￣）╭