I work retail. My boss knows he has to be extremely specific with what he wants me to do otherwise I take my own version of what he wants and do that, which may not be what he wanted.

He also knows if I am in the middle of something and he wants me to so another task as well, he knows that I always finish the first thing first, as otherwise it will never get done. So he may have to ask me to do the second task again later but more as a reminder like, "Hey did you do restock yet?"

Try to find what works best for both of you. Sounds like the person you were with was just not listening all together. Try to make it sound interesting, or at the very least important enough to catch their attention. My boss usually starts with something along the lines of, "If your bored I have plenty of things to keep you busy." But he has ADHD as well so he gets it and tries to help me out where he can with understanding what is asked of me because he sometimes needs the samething (he uses lists and they are ALL over the office).