Help! my 8mo old Amstaff is chewing my couch and the wood around the doors! What can I do that won't hurt her?

Try bitter apple spray. Sounds like she has separation anxiety. You could rotate the toys or try Kong toys with food paste that you can put inside to keep doggie busy. You may also think about a dog walker or doggie day care at least a few times a week. Or, try a dog trainer. Worse case scenario, they make medication for this that you can get a prescription for at the vets.