Sorry you're having trouble. We got a new kitten in November and he had the same problem for a while, but it soon cleared up.
Are the kittens all over the house? I can strongly recommend having a "safe room" for the kittens for the first month/six weeks they're with you. Even though they seem anxious to explore, a safe room is much better for them. It lets them get used to the smells and feel of their new home, and keeps them safer and calmer. It also helps you relax knowing there's less mess to clean when you get home!
You'll find the "safe room" technique helps with toilet training, too, because the litter box is right there and they have peace and quiet to figure out how to use it. Unless they're stressed/disoriented/sick, kittens are naturally inclined to use a nice fresh litter box.
You can let them out of the safe room little by little, and train them how to behave in different parts of the house. We shut the kitten in his safe room every night for at least two months I think.
I hope this helps. They're cute as anything but kittens can be exhausting!