My cat just fell out the window...

I've used a staged technique before - moving the litter tray closer and closer to the back door over a few days, then putting it immediately outside the back door. When this worked I then continued moving it further out in the garden to a patch of soil. Then I removed the tray and just sprinkled the litter on the soil for a couple of days. Finally I stopped with the litter completely, and had a proud moment as she shat right where I planned...

Sound advice.

Currently we are showing her the poop, yelling at her, putting her and the poop outside together, then telling her she's a good kitty and leaving her outside for a few hours.

Scoulding doesn't work very well on cats, you'd be better off using a fine water spray to discourage any bad behaviour. Moving the poop is a good idea.

Another tactic is to upset the cat's rhythm of which areas are waste and which are for feeding/sleeping. If you thoroughly cleaned the existing waste area and then moved a food bowl or sleeping basket there they will instinctively look for an alternative spot... this can be stressful though, so make sure the alternative's reasonably obvious and that you don't shift stuff around too often.