I would recomend using a small dull spur lightly, just to get your point across.
Try using a dressage crop and when your horse doesn’t respond to your leg lightly tap
If you use a crop right behind your leg your horse will respond
With my horses I teach them simple exercises such as leg yield turn on the forehand things like that which will get them listening also if I find my horse isn’t listening I just give them a light tap with the stick just to tell them hey I am here listen to my aids and it works 9/10 times
Hope this helps
Reinforce leg with a tap with the whip to encourage them to move off your leg, also not always working on the outside track of the arena forces your horse to listen to your legs as they cannot just follow the track around the arena. Hope this helps :)