We got our kitten 3 weeks ago. He had diarrhea. Thought it was from changing food. Took him to a vet and they started worming. That did not work. Changed food to low residue. The kitten peed on 2 different couches, a papasan chair, and my daughters clothes. We have kept him confined to one room for a week and a half. Tonight he peed on her bed. We are at our wits end. The kitten is a himalayan. PLEASE HELP

Kittens and puppies are a lot of work for a few weeks, and if you just confine yours to one room without people around, he's going to be even more nervous and untrained. Kittens of course don't really need to be trained much to use a litter box, so tell us about the litter box, how much you use, how often you change it, where it is, and how much you leave the kitty alone. All you really need is a big crate in the middle of the living room for two weeks, right amongst all the family, people to hold him and play with him and make him feel at home. He also needs to be around children who are calm, who don't chase him around and shout and make him nervous. Animals who pee where they aren't supposed to aren't malicious; there's something wrong with his care and handling.

So the problem is diarrhea and improper urination? Regarding the diarrhea, did the Vet do a fecal check? There are other micro organisns that can cause diarrhea that may require a different medication. And deworming may not instantly clear up the problem. Does he have his BMs in the litter box?
Regarding the urination, He is pretty young, but I suppose a urinary tract infection is a possibility, if not maybe he doesn't like the type of litter he has, or the location of his box. I'm guessing he is kind of small can he get in his box easily?
Kittens usually take to litter box training fairly easily, so this seems a little odd.
Might be a good idea to touch base with your Vet about these issues.

Litter is scooped several times a day. He is confined to my kids room as the vet told me to do this so he would not be confused as to where his litter box is. We go in several times per day to hold it, pet it play with it. It sleeps on my kids bed at night. My kids are 11 and 13. We own a horse, a bunny, and 2 dogs. The dogs seem to not care about the cat and the cat seems to want to play with the dogs. My kids, dogs, and horse are all great. The kids are girls who are homeschooled and are not rough. There is nothing wrong with the cats care or handling... your presumption is wrong. So far this kitten has cost me 2 couches that we are replacing and 350 in vet bills. Anyone have any suggestions??

I had an Aby, "headstrong" like your cat. I'm guessing he's trying to tell you something. At this point, I don't know what that might be.

I too wonder about the litter consistency (scoopable or clay? Similar to what he's used to?) and how easily he can get into the litter box.

Does he have empty boxes and paper bags to play in/hide in/sleep in? A scratching post?

He gets visited only several times a day? Himalayas (and Abys) are very social.

Hheath, our Cats expert, might be along later if she comes online. She will probably have some good suggestions and be able to figure this out.

I should not have blamed it on care. My apologies.
My cat started with diarrhea and going everywhere too, but I just accepted it based on where she had spent her first 8 weeks. And then it stopped. I had to be with her constantly.

I would agree that these issues are very frustrating, and my post may have been a liittle general.
I have had to deal with issues myself in my own cats, I too have been at my wits end with them.
So if I may be a little more specific, since my suggestions may have not been well stated.
First try to discern, medical vs behavioral.
Diarrhea can be caused by things other than worms. Only a fecal check will tell you that, hence my question regarding the fecal check. Just a guess on my part but a fairly common culprit in kittens is coccidia, or a bacterial overgrowth, only detected by a fecal exam, in either case meds other than routine dewormers are needed.
Maybe you could contact the person that you got the kitten from and ask if it has been a problem there.
Regarding the urine issues.
Himmys are more prone to kidney disorders than some other breeds, not sure if it would be evident in a kitten so young. That may be another question for whomever the kitten came from, regarding the parents and their overall health.
But if it is a problem for him, then only testing at a Veterinarians office will give you those answers.
I would think that given you seem to be a conscience and concerned client that your Vet would be willing to discuss these issues with a phone call free of charge.
As far as behavioral I am not an expert,and cats are funny creatures.
There is really no way of knowing exactly what could be going on over the internet.
Good Luck and I apologize that my earlier post may have seemed vague.