Potty training my 2.5 year old

Advice? She says she wants to go to the toilet and is on board and happy to go in there but when she sits up there she doesn’t try to relax and pee or says she’s done right away (we have had many successes previously with her sitting up and trying and successfully going when we would do it) and so now I know she isn’t trying... she just acts wild on the toilet trying to grab everything nearby like toilet paper and shower curtain and doesn’t listen which makes me go into a stern voice so she doesn’t get hurt and since she isn’t listening but I don’t want to create something negative associated with going to the toilet. Also, wondering how much I should push her to stay on the toilet, like if she says she’s done just get her down always? Or try to keep her there longer to keep trying. In the past when we tried and decided to hold off because she wasn’t ready she would say she was done and then go into the living room and have an accident.