Sweater hems folding up? (bought not made)

I am finding that I am having issues with several sweaters where the hems want to fold up and not lie flat, thereby showing the wrong side of the sweater. They are pretty much cotton or cotton blend, always washed on cold. It isn't one brand, but does seem to be more of an issue with more narrow hems.  I've tried lying them flat to dry, steaming, even ironing, but I can't get them to look nice.  I'm debating getting rid of several sweaters I would love to wear but don't because of this issue.

Does anyone have any advice? Is there something I maybe haven't tried? TIA!