When I started taking my son to church after his dad left, it was a challenge. We would go to the church close to us. One day his behavior was so bad, I left and drove over to another church where mass started 30 minutes later. I found that for some reason, he behaved better at the other church. We all have preferences as to what church, mass and priest we prefer and kids do to. I remember as a kid, I always liked Fr. Tom because his homilies were the shortest especially if mass ended close to the Bears kickoff time!
When I take my 4yo boy to church, we always "shake the sillies" out as we walk into church. It gives him a chance to release some of that energy. Our church also offers doughnuts after mass. My son is given his donation money and if he misbehaves, he looses one of the coins. If he doesn't have any left after mass, no doughnuts (this happened once and he got the point). I also pick him up during the prayers or sit down and move my fingers along the words so he can hear me saying them into his ear. I felt weird sitting when the congregation was standing, but I've gotten past that and have even had an older member of the parish compliment me on what a good mom I am for doing that.
We used to sit next to the musicians, but now sit in the first pew where he can see everything. I try to find younger children and point out that they do not know how to behave in church and that they are watching him to learn how to behave. On the other side, there are 2 "friends" in church that also sit in the front row that I use as examples of how HE is to behave. One is a grandfatherly man named Sargent Bob and another one is a young marine named Craig. We see Sargent Bob every week. He always offers my son the sign of peace and takes time after church to talk to him. Craig wore his uniform to mass the week he got out of boot camp. My son always wears a fedora to church and was intrigued by Craig's hat and what he did with it. After church we introduced ourselves and my son asked about hat etiquette. (we even stumped him when my son asked if being in the car is considered inside or outside when you have a hat ). These two men now set the example of how to behave in church. I will even say look over at Sargent Bob. When he stands, you stand. It helps.
Introduce her to the priest. Let her know that this is his church and like when you go over to friend's houses, his house, his rules. He expects you to listen to his stories and be quiet so others can hear them too. Don't you like when people listen to what you want to tell them? When you walk up to communion, he wants you to cross your arms so that he knows to say a prayer for you. Again with the doughnuts, Father always gets the first one, so no leaving early and so on. It does get easier and at 4 they will have their days, but I have learned that the majority of people at mass have been there and know what it's like