Annie I stopped wearing my wedding ring when I almost lost it twice (it reappeared in strange places after slipping off) I reckoned the third time I wouldn't find it again. Then a friend gave me a bit of "ring size adjuster" which is a kind of small spring-shaped spiral bendy nylon wire. Scissors cut it. You cut a piece about an inch long and wind it round the ring on the palm side, It thickens the shank and holds it invisibly against your finger. It has been brilliant!
Amazon has several versions of it, at about £3 or £4 a pack, enough to do all your rings.