If he's too focused on the treats in your hand, try setting a little pile on the counter in your kitchen and standing a bit away instead of having them in your hands. If he's exciteable, try doing everything in a low key sort of way. What happens if you kneel down next to him and stroke him calmly and then just sort of stroke upwards on his throat and gently press down back on his butt, not his back or hips....sort of tuck him into a sit. Then just hold him there and pat him or scratch him behind the ears in a relaxed way. Tell him "stay." He may not know that word yet. But replace him if he moves and say "stay." Then say "ok" and let him up. Tell him how wonderful he is and go give him a treat. Then come back and try again. Gradually increase the time he must stay. Most dogs love treats and they are a very useful tool.
When he acts too wound up and his behavior displeases you, walk away and withdraw all attention. Praise him when he acts the way you like. And be sure he's getting enough exercise. That is vital that some of that energy is released before training. He can't pay attention when he's all pent up.
You can put some treats in your pocket and walk along patting your thigh and encouraging him to come along, "let's go." You don't need a leash at this point. Just see if he'll come along. When he does for a few steps, praise and give a treat while he's walking. If he doesn't come along, don't bribe him with a treat. Just try to encourage him to come along with happy sounds and a little skip in your walk. LOL. After he's pretty good with that, you can add the leash. Then he can walk on a loose leash and you can add a sit whenever you come to a stop.
You can teach him to "watch." This encourages him to pay attention. Eye contact=treat. Use the same word every time and praise right away. "gooood watch."
Lying down is a hard one. A dog doesn't like to feel vulnerable and an older dog who never was taught might see this as reeeeeeeeealy odd...to be asked such a thing. LOL. I would work on the above things first and get him use to learning....kind of like he has to learn HOW to learn. Then when he is lying down on his own accord, just resting, you can say, "down." "goood down." And give him a free treat. He probably won't know what wonderful thing he did to earn a treat, but eventually something will happen where he does associate that word with the act. And even better, when you catch him going from standing or sitting into a down, say, "down." "Gooooood down." After a few days of this you can help him to "down." Hold a treat in front of him while he's sitting. This is assuming he's getting a little more civilized and not so wild. (after learning that this is school. LOL) Hold it in front of his nose and slowly bring your hand down to the floor. Keep it close to him so he doesn't stand up, but not so close that he has to back up to see or smell it. That will cause him to raise his rear and get up. You may need to try another way if he gets too silly and jumps up. But this usually gets the dog to bring his chest down into a lying down position. Say, "down." (just once) Don't repeat commands. He may not know this word so trying to associate it when he lies down on his own may work as a sort of head start.
You need to work him a little each and every day and keep at it. It will come together.
That's my little attempt at help. Maybe it will, maybe not. Good luck. I do believe you can teach old dogs new tricks. I've done it. If I can do it, you can. LOL.
I trained a 12 year old dog once and he was very willing and learned easily. But he wasn't exciteable.
