wow this post went in a weird direction!….
but getting back to Williams original question…
there’s a great experiment you should do regarding how far up to place your teeth.
this is really important cause the further we can go the bigger our sound can potentially be.
so the experiment, or practice exercise is to start where you normally do, then go up as much as you can until you don’t have any more control over your sound. at this point roll back just a tad until you do.
If you do this regularly you should eventually feel comfortable at a point that is higher than when you originally started, and then, you will have probably improved your sound. This doesn’t happen overnight so try doing it for a few weeks at least.
when I was young my great teacher taught me this and it really worked.