Our experiences are similar.
Domes kept backing out. Big ears. Had the biggest double dome, they just would not stay put even with locks.
So I went to molds with locks. Initial fit wasn’t to my liking. Ears got sore. Since I was 2+ hours from Costco, it occurred to me…I’m the one who knows exactly where the mold is hurting me. So over a period of days, I’d take a finger nail file and simply hone down the trouble areas. Did a little at a time, and 1-2 weeks later…they fit great.
The downside. I cannot understand speech as well with the molds. Had several adjustments done, finally the HIS person activated the old dome program…and instantly it was much…MUCH better. She said it’s not suppose to work that way but it did. Given that…I’m still running into situations where I simply cannot hear speech. I have the volume on these all the way up. I’m thinking of going back to domes as a ‘test’ to see if speech recognition improves. If I can get over this last issue of clarity of speech…I think I’m fairly set with my hearing aids after 1 year of getting them.