Well, this isn't my area of expertise, by a long shot. I have been lucky in my life and mine wouldn't bite a flea. I have a friend that has a male yorkie around the age of yours and he has an "attitude" as well.
The only suggestion that I can offer is exercise him to the max. Walks, and I don't mean leisurely walks, are very good for this type behavior as well.
Here is something I hope can help:
Who's Leading Who? Becoming the Leader
Your dog nips when you try to take a toy from him...ignores your request to exit the couch...or yanks ahead on walks. If you feel like your dog is challenging authority, then he probably thinks he is the "alpha" of the home. He needs to be taught a new, well-defined pecking order - and a new, lower place in the family hierarchy - for everyone's welfare. He needs YOU to become his leader. Otherwise, he'll rebel, growl and possibly bite when faced with a challenge.
Dogs aren't looking for a democracy - they're looking for leaders. Dogs want to know their place in the family pack and what their people expected of them, otherwise they're stressed. Most often, an "aggression" problem is really a "stress and confusion" problem. If your dog tries to dominate you or someone else in your household, it's probably because he sees role confusion and responds by taking charge.
"Alpha" is an attitude. It is not achieved by force or punishment. Rather, it is earned through confident, authoritative, consistent behavior on the part of the owner, who we prefer to call the leader. Dogs can sense who's in charge immediately; they are continuously reading your body language and are aware each time their people don't enforce commands. Notice how most dogs watch a good obedience instructor - and how they seem to wait to be given direction. They express respect and interest, not fear.
Then notice how a good obedience instructor behaves. He or she will walk with confidence...stand up straight...use a firm tone of voice. And that voice expresses commands as a directive, not a question. ("Come...? Come on, come...?") The dog realizes this person makes the decisions.
Are you rewarding bad behavior? Anticipate and remove opportunities for undesirable behavior. Don't let your dog dash out the door, for the accompanying feelings of joy and freedom are self-rewarding. Don't leave food on the counter, because if the dog grabs a tasty sandwich, counter-surfing has just been reinforced.
For dogs, it's natural to try to control their world with their jaws. Natural, but unacceptable. We need to regain control by using our minds.
How to reverse roles and become leader of the pack:
Step one: no more freebies. From now on, your dog must behave in order to earn the good things in life - petting, treats, meals, walks around the block. These are rewards you can use as you reinforce the new rules of behavior.
Use petting, feeding and playing as rewards. Before setting down the food bowl, instruct your dog to "sit." Say it only once. He receives his food - and enthusiastic praise ("Good boy!) only when he sits calmly. Pogo-ing from a seated position does not count. No "sit," no reward. Put the bowl out of his reach and walk away. Try again later. In addition, if your mealtimes coincide with your dog's, prepare his food first, but place it out of reach. Then eat your meal first before setting down his bowl. The leader in a dog pack eats first.
Subordinate dogs lick and bow to dominant dogs as a gesture of respect. So when you're working to modify the behavior of a dominant, unruly dog, reserve petting to use as positive reinforcement. To receive attention, he must obey a command such as "sit." Praise and pet as soon as he complies. If he prods you for more attention, ignore him. The idea is to convey to him that you decide when to begin and stop petting. The same should apply to playing, feeding and going for walks.
Lead the way, literally and figuratively. Starting today, don't let the dog bolt ahead ofyou out the door or drag you on walks. Keep your dog on leash, instruct him to sit, cross the threshold first and don't let him out until he complies. If he tends to push through the dog as you open it, slam it shut each time his nose approaches the opening. After 5 or 6 repetitions, he'll start getting the idea, but you cannot lapse and let him barrel out in front of you or he will resume the bolting behavior. On walks, strive to keep him at a heel.
Stay on a higher level than your dominant dog. During the retraining period, don't sit down to pet or play on the floor with your dog. Pet and praise from a level above the dog's head. In addition, at least until the dog learns his place in the pack, keep him off your bed and other furniture. He should stay at floor-level. On a related note, when you and your dog eye each other, as a leader you should hold the stare longer until he averts his eyes.
Stop the jumping. For dogs are challenging their people, it is important to discourage jumping up, as it is a dominating behavior. Ignore the dog, or command "Off" or "No." When greeting, give attention and petting to the dog only when he sits. If you later want to teach your dog to jump up (or get on the couch with you), you can, but the behavior should be on your terms.
No more playing favorites. If the dog ignores or intimidates another member of the household, let that person be the one to feed and dispense treats to the dog for now. It's essential that everyone in your family practices the same techniques while retraining the dog. Like a child, if a dog finds someone he can dominate, he'll do it.
Control the games. Tell family and friends not to taunt, wrestle or play tug-of-war - these games encourage dogs to dominate physically and to use their teeth. The outcome of games determines who's dominant in a pack. Instead, play hide and seek with a prized toy or fetch. As leader, you must be the one who decides when to start and end the game. Stop playing before the dog loses interest.
Use a crate. The crate serves several important functions. It gives the dog a secure den to call his own - a place to retreat when he wants to relax. Keep the crate door open when you're home so that he can enter if he'd like. The crate also helps you establish a new routine during retraining. Work on training him to go into the crate willingly, on command. Don't take "no" for an answer. To make the crate a welcoming place, start by giving him treats for going in the crate and feeding him in this area. Before training sessions, keep him in the crate an hour so that when you let him out, it will be easier to focus all of his attention on you. This practice also conveys that you, the leader, decides when he goes in and exits the crate. If your dog barks in the crate, ignore him. Do not release him until he's quiet and somewhat relaxed.
Diligently work at retraining so you can reach a point when your dog looks to you as the leader who decides what to do and when. And when you reach that point, don't slack off. You and the other human members of your household should always exude leadership and confidence. In most cases, if a dog knows he can depend on you, he will respect you and his new position on the family totem pole.
http://www.paw-rescue.org/dog_guide.php#s8