We have a biter, he has always been a biter since a puppy - it’s just the way his brain works. The best thing we could have done is put him down at 10 months, but just saying that out loud at home would put me in the dog house for a month.
I totally agree with everyone suggesting making him a second class citizen - all humans need to be above him on the totem pole. I’m not allowed to beat him, but he doesn’t get away with anything - I will chase him around the house until he gives up. Living a more structured life and having to listen to commands is a good idea. A lot of exercise helps.
I went right out at 6 months and bought the best three way e-collar I could find and that’s been the only reason the dog isn’t dead after 5 years of him nipping at someone once a week. While it’s true they know when the collar is on they have to be on their best behavior, he’s been better with age, but he still gets a muzzle when the grandson comes over, and may have to the rest of his life. He isn’t allowed on the couch if he has even a quivering lip. If he acts aggressively when eating he gets to wait to eat until the next feeding.
What has helped him around kids is me desensitizing him to having his face played with, ears pulled, and nose squeezed. On day one he growled at me gently pinching his nose, now a year later he actually enjoys having his face played with. If I’m watching him and he’s unsure about someone it’s automatic to distract him, usually with a tiny treat, and if he snarls he gets the collar, or gets squirted in the face with an extra large squirt gun. For some reason he thinks a ultraviolet light flashlight like is used to find scorpions is the scariest thing in the world. Finding what an individual dog responds to is key.
Our dog is still an idiot, but we know he’s always going to be like this and require extra work to keep him from getting his painted paw prints up on the fridge.