It always wants to ride up the sides of my bed because elastic never wants to hold it in place. When I wash and dry my sheets it inevitably spirals up in the washer and dryer so it never washes or dries properly. Then it’s a pain in the ass to try and fold neatly.
I feel like I’m failing adulthood after being bested by a bedsheet.
If it’s riding up the sides of your mattress, it’s probably not big enough for your mattress. Sheets say on the package something like, “fits mattresses up to 11 inches tall”. If your mattress is taller than that, it’ll ride up.