OTC Midweight Stretch Straight Leg Pants

I have several other pairs of the open to close pants and decided to try the mid weight. I ordered and bought the size I was used to getting the 38's. After wearing them once they seemed to have stretched out considerably, to the point they were way too big to wear out in public. I returned them and tried on two sizes down to a 35 and then bought two pairs, one sleet and the other black. I wore the sleet color and the same thing happened, it seems like they stretch out way too much to the point of them falling off or down. I had to take my belt off to walk through TSA checkpoint and my pants almost fell down if I didn't grab them.