She's being like that because she wants your attention because your not giving her enough. She knows that if she does bad things, she'll get your attention.

My ex's youngest was a terror but its not about punishing them. Thats what they want you to do. They want to get on your nerves to a point where you get angry and when you do, thats what they want.

Take a different approach. Sit her down talk to her and ask her questions about why she did what she did. See what she says and tell her its wrong. Don't keep getting angry at her cos she'll be getting worse every time you do.

Also it comes down to how much time you spend with her and how much you do with her. Cos my ex's kids dad wasn't about she was just out of hand and it took me a few months before i could actually stop her from doing naughty stuff. Eventually, once i started paying more attention to her and doing activities with her (painting pictures, cutting and gluing etc), she mellowed out and became a right angel.

Its down to you, if you keep telling her off, your giving her wants she wants. Number one cause of bad child behavior is strictly down to the parents.