What a great thread full of absolutely poor advice.
Some of you get it...but a lot of you scare me. I would not go for the "alpha roll" right out of the chute. That may be asking for a bite. Alpha rolls need to be applied quickly, firmly, harmlessly and only for punishment deserving of it. Noobs at dog training probably shouldn't try it.
What you've got sounds like a classic case of the dog thinking it's in charge, regardless of age. Age may exacerbate it, but it still doesn't excuse it. Sometimes dogs with arthritis, poor vision or other ailments may get cranky like this...have a vet render an opinion if any medical condition might be contributing. I'm sure when you're feeling poorly you're not charming either.
On the last page you also noted you don't trust the dog after a bite some time ago...another problem. If you have fear it will bite you, they will read that, and gauge you as weaker than they, so again, they are taking the role of alpha. Sounds like your gal is probably not in charge either.
Both of you need to take control back. If you get the Nat Geo channel, start watching Dog Whisperer. It works. I use it. I'd recommend a simple start by having a leash on the dog. When he's on the couch and you want to sit there, ask him to get off. Refusal=a pop of the leash. Repeat, calmly, firmly, patiently. He can growl all he wants to, but eventually he'll get tired of being tugged on and get off. You're claiming the space. Claim space everywhere in the house. He's in your way? Ask him to move, and push him lightly with your feet until he moves. Most importantly, never let him see you sweat. Calm action, little talk, never any shouting. Dogs respect the strong, silent types the most.
These methods are difficult to explain in text. If you don't have NatGeo you can search YouTube for "Dog Whisperer" and "Cesar Millan" and watch a few segments. It should help cement the idea. Never, ever use physical strength/violence...there is a huge difference between the 'touch' he uses and poking/hitting the dog. Took me some time to master it.
Dogs that growl/bite are not inherently evil. I no longer fear them now that I have a better understanding of how to deal with them. 90% of the time they are a problem because the owners have not established or have relinquished authority.