Sorry, automatic corrector. So, with time, your horse will try flying changes.
Fiesta, when cantering, make a preparatory work, by changing lead using trot, then ask for the opposite lead. Then do those shifts faster, (less trot between changes)
Place a pole in the middle of the ring on a diagonal..( like you would put a jump) and one on the other diagonal. And push for the change when u jump/ canter over it. Put more weight in the stirrup that you want to go. And maybe even open up your reins to the way you want to go. Hope you figure it out ☺️
First of all you have to shift your weight on the opposite side to where you go.
First do a series of simple changes in X in a giant figure 8 and then start shifting the shoulder to the opposite side from where you are going and the hindquarters to the inside of your turn.