for the alto sax, should i just my emobochure when playing high and low notes?

thanks

NO! your embochure should stay the same, and you should use your diaphragm to support all notes.

When I met Benn Clatworthy (pro-saxophonist) he done a thing where he stands behind you and plays the notes and you just blow a constant supported stream of air into the sax, and you go all over the sax and nothing changes in your embochure.