Poorly fitting rings

How do I stop my half eternity ring moving round all the time? I`m constantly having to readjust it.

Thank you, ladies. I did actually try those, unsuccessfully, but will give them another try.

I brought ring tighters off eBay they are spirals of plastic you can wrap round your ring . You can do it without taking off your ring. Work brilliantly and if your fingers swell just easy to take off. Once mine is on don't take it off for messy jobs as they are washable.

Ring size adjusters Invisible Tightener (spiral plastic) easy to apply I would recommend on Amazon different widths they are not expensive.

I'm just about to order a keeper. It looks like a spiral bit of plastic. We'll see.......