If it’s the string around the pants then you can gradually work it out with a pin, and to stop it just tie a bigger knot that won’t fit through the hole. But that mightn’t be what your talking about.

It isnt the string, it’s the elastic :(

If it’s worth the trouble to you to open the seams, you could replace it with a wider and thicker elastic band that would be less likely to do that. You could also try narrowing the casing so it has less vertical room to move and twist in. But it’s still probably going to happen some.

I run a line of stitches vertically at 12 to 15 inch intervals so it simply can’t fold over. A small pain, but worth it to avoid the pesky rollover.

@JilltheTooth, doesn’t that prevent the elastic from having enough give? I used to do it in two places, just at the side seams.

Not really, because it still has full range between the stitches. When I make my elastic waist pants I usually do four, front, back and both sides, I can still still get them over my…er…ample…posterior and the elastic never rolls.

@jillthetooth thank you, that seems easy enough. Better than my idea of quilting it…which would ruin the stretchiness.

Glad to help, I’m all about the easy road!