I know a lot of people say this is a no no but long and low and wide hands have always helped me a lot when it comes to teaching a younger horse to flex and reach for the bit themselfs. A lot of times people try a force a horse to use the bit.
We lunge the youngsters with a girth or cord to help them get used to some pressure on the bit and go into a frame. With riding we don't fuss too much about it, just work on transitions and impulse, and always reward and release when the horse relaxes into a frame. If you are having trouble see if there is someone nearby with experience who can help you out 😊