Button sticker

So believe it or not this is the closest conversation at all I’ve found anywhere on google to my problem. I bought a bunch of those 3d stickers for my iPhone button. Nothing wrong eith the button itself, just stickers for looks. A few of them I have though aren’t sticky, and I’m not sure if there is somewhere I can buy the little round double faved sticky pad to put on it, or what that’s even called.. I don’t think I should take my chances with glue? I do use a passcode though so I really don’t use it for the fingerprint but still don’t want it to not come off. Anyone know of anything I could do?