[Chewie1]

We had a similar problem with Chewie. Because we taught him down from sit, we would always do sit and then down and it became a habit so he would just go down automatically. Since he knows sit pretty well, I would now focus on down. Avoid using sit for the time being and just give the down command, and only treat when he's down. Try not to run the two commands one after the other when training and keep them separate and mix them up. If you want to do 3 X 5 mins of training a day for example. Do all sits in one session and do all downs in another session so he can learn the difference between the two.

Hope this helps!