Well try to move the button at the waist. See if there is any fabric at the crotch seam to let out.....probably not. I don't know of anyway to do this easily, sorry. Salena

Thank you, salena. I was afraid of that. So they stay in the closet as a reminder to return things that are not satisfactory.

Can you let out the inseam (inside leg seam) at all?

You might try this:
Turn the pants inside out. Now turn one leg inside the other. See the "U" shape the crotch curve forms? Try stitching a curve a little deeper than the one manufactured, say, 1/4 inch deeper, and taper it to meet the original seam at the bottom of the fly in the front, and maybe 1/3 way up the curve in the back. Trim the extra fabric, a tiny bit, because if you don't trim the fabric you won't feel the extra room you've made.

You might think that you're "taking it in" and making it smaller. Not at all. If you think about geometry class in high school, imagine you're making room for a bigger sphere. It would be a bigger circle. It doesn't have to be much bigger, to look at, to have a much larger measurement.

evaf, thank you, thank you, thank you. This will do the trick. I would have thought of this myself, but I dreamed my time away in geometry class and anyway, it was too many years ago. (:-)