How do I change the "windows' key to the "ALT" key and vice versa?

Question

I want to the layout of my keyboard because my left thumb is used to resetting by the "alt" key on a full size keyboard. But this new keyboard I got is much smaller, so my thumb now rests on the windows key. I would like to swap the "alt" with the "windows" key. Can someones please help? Thank you!