8 week old kitten and runny poos

I got a 8 week old kitten 3 days ago and she has been having runny poos. The lady I got her from said that she had been wormed but could do with being done again so I did this on Saturday, she hasn't been vaccinated and she is booked in for those on Saturday, she will also meow when doing a poo in the tray but doesn't seem to meow when doing a wee.

I asked the lady I got her from what her poos had been like for her and she said they were fine and could be the change in food I'm feeding her whiskers 2-6 month kitten wet food and kitten dry food The lady sent me photos of what she was feeding her and I noticed that she was feeding her adult cat food and not kitten food

So I'm in a dilemma about the food situation now in case it is the food causing it whether to stick with whiskers kitten food or to put her back on what she was being fed before even though it is adult cat food? Today will be the 4th day I've had her and there's no improvement in her poo.

I was just after some advice to see if I can improve it before she goes to the vet so I can at least rule things out beforehand. It's not very nice for us both at the moment as she stands in it when she turns around to cover is so I have to wait with a baby wipe in hand before she get's out the tray and she doesn't like me wiping her feet! lol

Kitten food is richer than adult food, so could be causing stomach upset. That said, she does need the nutrients in the kitten food. Can you get some of the original food and transition her more slowly?

She is so young!  Congratulations on your new baby.  What I would do is get a small bag of what the lady was feeding her and see if her poops firm up.  (I'm assuming it's dry food.)  Then, introduce a high quality canned kitten food, which will be much easier on her system and easier for her to eat.  I always like to give my babies Royal Canin kitten (canned and dry).  Once you get the food situation down and her poops firmed up, you can add some new food to her old food and then work to transition her over to the new food.