*** any DOG trainers here??

Our family dog, that was adopted by us is not very bright. She's been living with us for several years, mostly outside (it's a warm climate), we take her in when it's cold outside.
Also, she is well natured (doesn't bite or growl ever), she is large (the size of a lab, maybe larger), untrainable, very chaotic, jumps on everyone, scared of noises, doesn't listen, jumps over 6 feet fence to roam around the neighbourhood. Her previous owner was actually relieved that we wanted to adopt her (she was found running around on the street, we got her ID-ed at the shelter through microchip, her owner said - go ahead and keep her - I can understand now why he said that)....
I had dogs in the past that were very intelligent and very trainable, and this one is just the opposite, and I don't know how to deal with her, she really frustrates me. It's my spouse's dog, not my decision to have her - too much stress already. He just lets her be, but since she is so large, just letting her be doesn't work.

Any advice on training or at least learning to become more tolerable to her so many shortcomings? She is about 6 years old now, probably way beyond training stage - I tried many times (and I used to train my other dogs myself when they were puppies).