It can be due to litter box's location or due to the changing of brands. Keep 1 kind of brand and she should get used to it. Whenever she uses the litter box, praise her and give her treats. What I used to do with my cat whenever she was about to use a different location for a litter box, I gently put her in it, and if she tries to leave, I put her right back in it, I keep doing that until she gets the idea and finally uses it.
I also used to return her to the litter box to cover her feces when she leaves it (when she was a kitten) and either let her cover it by holding her hand and making her cover it, or I cover it myself by using a spoon, and after she gets out she gets a treat or tuna bite or anything that she loves. Now she's all good and never uses a different spot. But don't make it very stressful for her, as it gets kind of stressful for a cat to be forced to do something. Be very gentle. Also keep in mind that if you don't clean the spots she used to do her business on really well, that may encourage her to go there a hundred times more.
So for starters (if you are able) change the location of the litter box and leave it where you put it. If it's an open litter box, don't push it all the way to the wall, as that will make it harder for her to use. Keep it in an undisturbed space in your house. Clean the spots in your kitchen very well, possibly with a urine smell remover. And finally don't allow her to use the spots again. Whenever you see her trying to dig or displaying the ''go to potty'' stance, carry her and put her in the litter box, and if she gets out put her back in. However, don't block her way out, wait until she gets out and then put back in. If you block her way out, it may only get her stressed and won't know what to do. If she doesn't get the idea dig the litter with a spoon or if it was brand new and clean do it with your finger, that not only gives her the idea but also triggers her instinct to use the spot, especially when she needs to go so bad.
After that, let her find her way out and when she comes give a treat or a delicious bite of the food she likes. Don't make it a meal, though, just enough to make her want more the next time. Of course if she isn't trained for anything yet (like most house cats) she'll need time to figure out that she only gets the delicious thing after she uses the litter box. Of course also give a treat to her whenever she uses the litter box without your help as well.
By saying all that, it's easier to note that basically what you are doing is to retrain her to use the litter box.
Of course all those considerations should be taken after the cat is checked by the vet to make sure it isn't a health issue that's causing all this.
Wish you all the best.