LOL actually I would find it to be a little humorous. Can you imagine the bewlidered looks on their face when they tell him one command but he does another instead?? LOL

You're right though I was goign to add but forgot to that it would be most confusing to you. BUT PERHAPS introduce a new word to the command to maybe "fix" it?? Like, he's quiet when you say "speak", so say "quiet speak" and eventually wean off saying "speak" so you just have to say "quiet" and he'll obey?