tired of yelling

One of the things that my older boy has a problem with is detecting when my husband and I are angry at him for something he's done. By the time we yell at him, he does know (kind of), but I don't think he understand what us being mad at him means. I can yell at him, scold him harsh, whatever, and two seconds later he's singing to himself, not a care in the world - it's like talking to a brick wall, only he doesn't understand, I think. We don't even really know what the deal is.

He's also very oppositional, but not violent. I've thought about the whole Oppositional/Defiant disorder (yes, there's an actual "disorder" that is often times paired with ADHD) but I'm not sure he qualifies, even if he displays a lot of the "symptoms". Besides, aren't kids usually like this? That's what I thought. But talking with friends I think it's safe to say that there are kids out there who do not behave that way. And he's not necessarily "violent" - at least not on purpose. But he does lash out and flail about like a toddler throwing a tantrum, so...

If we need to explain something to him, and it's not what he's expecting or he doesn't like the way the conversation is going, then he will insist on breaking in to express his disapproval. We don't let him get away with this so we tell him to "Stop Talking" every time he breaks in with a "But..." This cycle of "Stop Talking", "But", can go on for several repeats, one right after the other and usually resulting in either my husband or me losing it and yelling our brains out for him to just "Shut Up". Even then he doesn't stop. I DON'T FUCKING GET IT! Why does it have to come to me screaming in order for him to actually STOP doing whatever it is we're telling him to stop doing?

I was talking to my husband about this earlier. I said that whenever we scold our 1-year-old he responds with a sad pouty face that's struggling to hold back tears. If it's serious enough then he'll cry, cover his face, and even become embarrassed to look at us. Not my 6-year-old... he just doesn't get it. (I'm trying to remember if he ever did this and I want to say no, but I'm not totally sure.) We all just don't get it. And we don't know what to do about it. Like I said before, talking and explaining doesn't do anything. So I hope it just gets better with age. Unfortunately, it seems that his situation has only gotten worse with age.