What are you feeding? I've saved quite a few bleached corals, but for some of them, getting them to eat is difficult. If they won't eat, then they probably won't make it since they don't have zooxanthallae to give them the sugars they need.
The problem is that bleaching can have *so* many different causes: high light, extreme low light, temp, poor water quality, and possibly even the lifecycle of zooxanthallae itself.
Is your coral QT the same one you mentioned above (10g Wally world special?) If so, that would make sense that they are bleaching more in QT since the light on those tanks is next to none (and isn't the correct spectrum.) If you seriously want to rescue corals, I'd set up a good coral QT...with the correct lighting and plenty of live rock. When you say they heal right up in the main tank, I'm guessing your QT tank is the problem.
If they still won't eat, try other foods. Some are pretty finicky, and it takes several tries to get a response. Never force feed. Try amino acid dosing before the lights go out, then feed an hour or two after dark.
