I've always noticed overlocks are used on factoray made stretchy stuff, but will the seams actually stretch? Do I need to change the settings/tensions? I guess what doesn't make sense to me is that the regular straight stitch on my regular machine doesn't stretch and wil break threads if you pull the fabric to stretch... how are the straight stitches of the server different?

I'm such a dunce with these modern fabrics... LOL!