Help! Feral cat, new house!

Let me start at the beginning.

We got our little calico Gumbo about nine years ago from a woman who no longer wanted her (I say that loosely because the woman planned to shoot her). My brother and I took her home and kept her as an inside/outside cat (she ate inside and used the bathroom outside).

She never liked people, she was always very shy and timid. Any time she was ever in the house for any period of time, she would pee or poop on the furniture.

Well, all we did was keep her strictly outside, although we have two large outside dogs, she stays away from them, but stays close enough so that she's at home.

Now we've moved into a new house and since it is an area that is new to her, we thought it would be best to not let her outside for fear that she would run off and never come back. 

We tried to litter box train her and she used it once and I was so proud of her! Then this morning she pooped on my parents' bed...

I need help! We've had her for so long and she's probably about 10 years old now, but she's very unfriendly and has problems using the litter box properly!

I know moving her from outside to inside was a big transition, but we didn't want to lose her! 

HELP!  

I would confine her to a large cage or bathroom with her litter box until she gets used to using it consistently, and then gradually let her visit the rest of the house in progressively longer intervals. This will also make the new space less overwhelming for her.

If you want to work on fully socializing her, this is a great method to follow: http://bestfriends.org/resources/socializing-cats-how-socialize-very-shy-or-fearful-cat

I think it's great that you're keeping her inside. It will be much safer for her! And you definitely don't need to give her up, even older cats can learn new things! In the end she'll likely be much happier with her new life when she learns how safe she is.

She may never adjust to being an inside cat, but she needs to be inside for at least several weeks until her internal GPS adjusts to her new location.  Otherwise she may try to find your old home and return to it.  Having the run of the house is too much for her, and most ferals do best when confined to one small room of their own (a study or something without beds to poop on).  Having a litter box with Dr. Elsey's CAT ATTRACT litter is a good beginning.  Also, have TWO litter boxes, as some cats, particularly ferals, prefer to pee in one place and poop in another.  Two boxes allows them to do that.  We often start out ferals in a large dog crate where there is room for their bed, their food & water, and their litter box, obviously at opposite ends of the crate.  We cover it with a sheet so they feel as if they are in a safe cave.  When they are calm, we start leaving the sheet off one end so they can see us when we move around the room (always away from any other animals or noisy kids) and get used to us.  It sounds like she is basically a feral cat so read things in the Ferals Forum here and you will get some more great ideas about how to acclimate her to your home.