When im loping my horse and I want her to stop quickly I pull back and she pounces two or three times on her front legs to stop instead of putting her back feet a little under her and putting her butt towards the ground... It is very uncomfortable for me and hard on her front legs so I want to learn how to make her stop on her butt! Also, I barrel race her and it would be better if she turned more on her butt instead of putting all her weight on her front legs as she turns, any idea's?
She bounces because you pulled back and she is on the forehand. In order for her to work off her haunches, you as the rider have to teach her and you have be in the correct position. In order for you to teach her, you have to learn yourself which requires live, hands on instructions from a coach, trainer, etc. Online written instruction will do you more harm than good here, sorry.
Timing is important when asking a horse to stop smoothly from any gait, but especially the canter. At the canter the stop works well if cued lightly while the front feet are off the ground. Paired with the word, "Whoa" or whatever is acceptable to you and a slight shift with your seat.
It really helps your horse if you stay balanced. If you find yourself being tossed back or forward, you may need to rethink your whole seat and balance.
Learning to feel where your horses feet are can be challenging but it's a cool accomplishment and opens the door for better movement for you and your horse.
I would suggest that when you stop her you do not pull on her, as has been said. With my reiner, all I have to do is swing my legs forward, plant my butt and say whoa. This was in place even before he ever learned to slide. To get him to stop more on his haunches, we stopped him ,and immediately backed him up so that he stopped on the rear ready to go reverse, rather than the front.
Once you get him on his haunches, the roll back becomes a little easier. My biggest mistake is rushing it. Wait for your horse. Stop, pause slightly, ask the horse to turn and don't get ahead of it. As has been said-you really need a trainer to do this right.