I use an Imus comfort bit, which has a lot of relief, curb bit. When I first started using it I had to put it higher in Vidas mouth than I normally would because she was getting her tongue over it. If I remember right I had 3 wrinkles in her mouth when I normally just have the bit sitting in the corners with little to no wrinkles.
This is the one she can get her tongue over
This is one she can't
You might want to go to one with less tongue relief or tighten your headstall.
I just kept checking Vida during a ride. If she was still getting her tongue over I'd go up another hole on the headstall. I felt terrible to keep tightening it up but after she got used to it and stopped playing, I could move it down to just in the corners, no wrinkles.