A.B.
Hi R.. My son does the same things sometimes, and I used to get frustrated and scream at him too but you're right, it really doesn't work too well, and it sends a wrong message also. I noticed a couple of times after I had yelled very loudly my little one raising his voice when he didn't get what he wants. I agree with whomever said to try and ignore his behavior, depending on what he is doing. Especially if your 6 yo is around and watching, he very well might be trying to impress or get the attention of your older son. We do time outs with my son, he's 21 months and we've been doing them for 6 months at least I think. At first they didn't seem to make much difference but now he knows that he's made a mistake. If my son repeats the behavior after his time out, he gets another one, and if that doesn't work, I shut him in his room for a few seconds. This is not as long as a regular time out on the couch but it works and I have only had to do it twice -- he hates the door being shut on him.
I think that consistency is key, that you react the same way each time, even if it means he spends a lot of time in time out at at first. Acknowledge his good behavior. Also, it might be worth thinking about picking your battles. This is something my husband and I talked about a lot for a while. Clearly, we draw the line at things like hitting and biting, those are automatic time outs, but some other things that kids do to test their limits just aren't worth fighting about, at least in my opinion. Good luck with whatever you decide!