You need to get this horse's respect on the ground before you attempt to sit on her. She is going nothing but disrespecting you. Get bossy.
I would agree with you but there are ponies that can have all the ground respect but have learned to ignore it when ridden!
I was running a busy riding school/livery yard many moons ago. I returned from exercise to find a grey pony tied in the yard.
I knew exactly who had left it there! It was a friend who was also the local knackerman. It was not unusual for him to pick up a pony to be putdown, usually with laminitis. He would buy it and send it to me to see if I could get it right.
I was expecting this fat Welsh pony, all of 11.2 to be laminitic but, he showed no signs.
When I spoke to friend on the phone he told me that the pony was unrideable but, that I could probably sort it.
Pony was very well mannered, accepted tack, lunged, long reined without fault. Put a rider on him and even with me holding his head up he could throw that rider 8 feet to the side!
I had four different rider come off him in the space of an hour - after a good lunge workout.
I had a ride to take out so left the older children to keep getting on it and to ride the heck out of the little beggar.
An hour later it was still dropping them all but, it was getting tired.
I told the children they were useless and to bring it to me.
I stepped on it and set to whacking it both sides with two dressage whips. I sent it off at a fast canter. It went around the arena twice and then int the corner it threw itself on the ground - at the canter! I was not quick enough to do anything about it other than to step straight back on. Next time I was ready and landed on my feet, pinning pony down. I had all the children pile on top of it and stay there for some minutes. When allowed to stand I was straight back on and he was fine. The kids kept riding him with no problems. A month later I was using him in Riding for the Disabled.
That pony was sold several times but stayed in the yard. I had moved on and coming home for a break I went to a show to catch up with some friends.
I was stood by the minimus jumping when a pony came in a deliberately dropped its rider into the first fence. He did this twice and I remarked to my friend "What a dirty little pony!" Her reply was "You should know, that's Breeze!"
I never recognised him as several years had passed and he was now totally white.
I was in the arena, took his reins. Put the child back up and told Breeze in no uncertain terms that he had better behave - or else!
I ran leading the kiddie over three or four fences and then let her go on her own. Breeze went around beautifully and when the girl went to ride out the ring Breeze turned and trotted back to me.
Ponies are clever and will use their brains to get out of doing anything if they think they can!
Often naughty ponies come really good when the rider has outgrown them and has the strength to make them obey. That pony can be sold and immediately revert to naughty because of a small rider.
Seen it so many times.