The older-style head covers had elastic drawstrings you could use to tighten the mask around for better fit around your forehead and cheek area.
Some of the newer ones don't have the drawstring. They do have a little looser fit to them. You could try a baseball hat/stocking cap/beanie over them to help keep it in place, or layer it over top of that too.
One thing I do, since I like to hear when i'm in the woods, is pull the eyehole opening back over my ears. This kind of keeps the whole thing taught to my face a little better. Looks goofy as hell... but that's the least of my worries when i'm out hunting.
I think the activated carbon fabric prevents them from using really stretchy fabric for the facemasks.