I have the same prob with my lab mix. She is only 15 weeks so i can't expect too much training right now but we are working on it. We have stopped most of the jumping by telling her NO! very firmly and she stops, however, when she gets really excited she will run and bite the back of my ankle really hard and then as if she knew she did something wrong she will run away. LOL I definitely dont condone this kind of behavior so as soon as she does it i grab one of her toys (that are always lying around the house) and give this to her instead. She also knaws on our hands when we hold her but i try to have a plush toy around and redirect her biting into the toy. She is learning but its basic lab upbringing. They chew EVERYTHING! Good luck on training and remember patience bc they are just babies and new to everything. Always have toys around to redirect and reward, reward, reward when doing right.