Unfortunately, most shelter dogs find them selves surrendered around 8 month - 1.5 years of age. This is prime adolescence period. Dogs don't grow out of unwanted behaviors, they just get better at doing them. The more dogs practice behavior, the more permanent it becomes. During adolescence, dogs become more impulsive, destructive and over all harder to handle.
Most owners will have to step back and redo a lot of their training at this age. Even if your dog was good off leash in the juvenile period, you may need to put him back on leash and practice recall for months, before you let him off again.
Don't give up! Adolescence in dogs doesn't last nearly as long as adolescence in humans (unless you own a husky). Come to extra classes, give your dog some extra chews and you will pass this stage.
Mental stimulation is the best way to tire your dog. Training is the best way to achieve mental stimulation. A sleeping dog, is not chewing your couch. When you can't monitor your dog, keep him behind an x-pen or baby gate in a dog proof space. Be sure that she has lots of chew items. Most dogs would much rather chew a tasty bone than your coffee table.