Appropriate consequences?

[hiddeneverything]

I have a 4 yo DS. Everyone says how great he is, how clever, how well behaved and that I should be very proud.
However, ever since baby bro has come along 9 months ago he is a different boy. He can still be lovely, but also moody and cheeky, and talks back all the time. I tell him to stop doing something and he doesn't stop, I tell him not to do something and he does it. He didn't used to be like this. It's things like kicking a ball indoors, throwing things, being rough/over zealous, and not doing as he is asked. It's really beginning to upset me as this isn't the boy that I know.
I try so hard to have regular one on one time with him, he has an early bed time, eats healthy food and also a good balance of treats. He has a good balance of time at home and days out/clubs. He just seems to be really spoiled and moody now and I don't know where I've gone wrong. I try to give him lots of positive attention but I end up spending half my day giving him a row. How can I stop this before he becomes a "naughty boy"? And what can I do differently?

[JiltedJohnsJulie]

What happens now if you ask him not to do something and he still does it?

[April45]

He's spent so long being your number one, he's had to be number 2 especially when baby has been younger.

Think if there's a pattern to this behaviour when you are engaging with your younger child. And attention is attention for children so being told off is meeting that need. Your 9 month old should be able to fit in with 4 year old now, perhaps try a few days focusing on 4yo routine and see what happens.