I've seen some implant that use hearing aid earmold.. I would love to use the skeleton-type of earmold to hold it still. I seen some snugfit, and I think it look too tight on some people. they are better off with an skeleton earmold.
Adding an extra magnet in your headpiece help too especially when you have thick hair. Also, if the hook around your ear is too long or short, it will fall off too, so you need to make sure it is the right size for you for it to stay put.
oh another thing that make your processor/headpiece pop off is if the wire to your headpiece is too long or short. If it too long, it will push your processor off when you lay down.