3 Year Old Potty Training Accidents - PLEASE HELP

There are a few things going on here. Remember she is only 3.

She may have seemed trained, but in reality, she was being given clues from someone when she needed to go.. or at least needed to try,

The other thing is, this can be normal.

Children learn a trick, get a lot of praise and then, they are over it.

She just needs to be guided and reminded further. Yes, it is a hassle and frustrating for you, but she is still very young and is not totally in tune with her body.

She is probably about to go through a major growth spurt and is just not interested in stopping to go potty.She does not want to miss out on her fun.. going to the potty takes time away from everything else and it is boring and messy.

This is not a defiance thing, it is being 3 years old and very busy in her own little world.

Hang in there and when she does go on her own, praise her, praise her.

Do not make her feel bad about these accidents, just reassure her you know she can do this. And thet it is quicker to go in the potty than to have to stop and get cleaned up when she has an accident.

I would see if you can keep her on the potty longer. Bring a book and keep her company while she sits. If there's a time of day she is more likely to poop, especially do this then.

I would continue to take her to the potty when you think she might need to go. I would also look for things that might encourage her to sit as long as she needs to - a footstool to rest her feet on, a book she can keep by the toilet, etc. Did anything else change in the last 2 weeks? New routine?

And who does all of the cleaning up after the accidents?

It sounds as if there is no "reward" for her to make the effort. In the very beginning, treats or prizes or stickers or whatever can work as a small reward. But as they become more capable, then being clean is its OWN reward. But it may not be enough. Maybe her reward can be that she doesn't have to clean up poopy panties.

Did something happen while she was pooping on the toilet?
Does she seem to fidget when sitting on the toilet for a longer period of time? If so, maybe her legs are falling asleep or she wants to hurry back to a toy, game or TV show.
Other than telling you she knows she needs to poop on the toilet, what else does she say when you ask her why she is going in her pants instead of the toilet?
Have you tried offering incentives like "Potty Treats" or a special outing if she uses the toilet for several weeks without an accident?