I got this tip from @Murrydog :
> I had the exact same issue! I resolved this by not pushing the ear piece into my ear. Just hold it up to the ear and gently rotate about 15°. You may have to try several times to get the hang of it. The soft rubber will seal up to your ear without any pressure on it. Give it a try, took a week or so for me to get the hang of it.
I let my ears heal for a few days and tried it. It works! I had been doing this all wrong, by mashing the ear tips farther into my ears to get rid of the feedback noises, which worked but left my ears being more and more painful and after awhile, stopped working in my left ear.
Using Murrydog's suggestion, after experimenting with eartip sizes a bit, I am now not squeaking and not hurting!
I wonder why nobody ever told me the brute force method does not work, and the nice and gentle method does? Anyway, that seems to be the solution (2 days so far).
Thank you, Murrydog!