I can't find a comfortable position? ?

Nice subliminal advertising.

Try putting something in between the laptop and your lap, like a pillow or a laptop tray thing. That way, your lap won't get warm. Either way, the laptop will get warm, so the only thing you can hope to do about that is reduce or redirect the heat. Otherwise, try setting it up on a desk as if it were a desktop computer. Place it so that the screen is about eye level.

Bean bag chair, maybe? Have you tried putting a blanket or some other type of insulator inbetween you and the laptop on the couch?

Or, if you're willing to shed 25$, you could invest in VGA cables so that you could play your laptop on the TV. Then you could use whatever position you wanted, so long as the game isn't keyboard-limited. (Mouse can go anywhere, as well as USB Controllers - you can have an external keyboard as well if necessary.) Link to VGA Cables is posted below - I'd make sure your Laptop is compatible before ordering.

If you are hunching over because you are having trouble seeing the screen, then you may need to get reading glasses (just for while you play) that way you can lean against a chair and not hunch over.

Ikea has a good laptop table thats adjustable for around $20.

maybe put something underneath the laptop so it doesn't get hot while you lie on the couch if that is comfortable