I have 2 10month old rough collies, one of which has turned into a monster over the last 2 weeks. He now jumps on the sofa which he didn't do before races
us up the stairs and then is aggressive and excitable trying to bit our legs and last night he did the same when I went to get into bed. We tried loud noises
as a distraction but all that does is excite him more and frighten our other lad.
Water spray doesn't work as he loves water. He also turns on the other one when he is getting worked up.
I know I could shut him out of the rooms etc, but I'd rather face this head on if possible as he has become generally less well behaved, although he waits for me to go through doors before him and sits and waits nicely for his dinner.
Any thoughs?

He's a teenager!!! Keep doing what your doing, he will learn but a bit more slowly at the mo, castration can calm them down ( testoserone levels are very high) but keep training.

Try a time out session when he does start, but only for a few minutes at a time. This usually has the desired effect.