I bought a piece of 1.5 inch stiff foam to try to fix a sag in a bed. It didn’t work but having that thick piece of solid foam around has been a life saver.
Need something flat to put a laptop on? Throw it on the foam. Going to be doing something that requires you to be on your knees for a while? Get the foam!
It went from stupid purchase to something I’d gladly replace if it broke.
As for them staying in your ear, do you pull up on your earlobe when inserting normal ear plugs? I discovered this a while ago and it took in-ear stuff from being absolutely unusable to working great.