How do I stop the dog from snagging food when we arent looking?

Train her to leave it. Make her keep a respectable distance when you eat. She needs to learn impulse control. It takes time, but is totally possible. If she is very new she is simply asserting herself. In a pack, when the dominent leave the meal, the subordinates are allowed to eat, so she needs to know you still claim the meal. When your finished create her meal. I use carrots, and they are fed only from their bowls. They know th ritual, and don't dare steal my food. I also feed them their two meals after ours. Breakfast and dinner. Never before, and never scraps off the table.