You have to leave the public place. You go sit in the car and you turn your back and let them scream it out. No talking, no "rewarding" the tantrum with ANY attention--nothing.
This is it. Take her to the car, strap her into her seat and let her scream until she can't scream any more. You cannot reward the behavior by speaking to her at all, negative, positive or neutral. Squash the urge to tell her she needs to stop screaming, or that she can get out of the seat when she is done, or anything at all. When she is done take her home. Once you are home you can try to explain what she did wrong, and the consequence that ensued. I have found sympathizing at this point works well. This goes for church, the grocery store, restaurants, etc. Be consistent, do it when she is someplace she probably doesn't want to be as well as places that she will be upset leaving, but is misbehaving for whatever reason. Eventually she will put two and two together that her behavior is leading to a time out in the car until she calms herself and then a trip home.
DD2 was the more difficult of my children. We didn't really eat out until she was 3 and a half?! She rarely went shopping with me either. For whatever reason home was her happy place and I happily left her there. It was better for all of us. We called it the terrible twos and the torturous threes. Then it started to get better and we could go do simple outings without a fuss.
Bribery may work too especially as she gets a touch older, but that is a slippery slope that can sometimes backfire. Then you have a temper tantrum because they didn't get the reward they thought they were going to get or you didn't stay at the park long enough or whatever...

Just know that age does bring maturity. Some kids get there more quickly than others. Good luck!




