Answer:
I mean goodbye for South Americans.
I keep things green and keep kids happy during summer time.
Every night I'm told what to do, and each morning I do what I'm told. But I still don't escape your scold. What am I?
What can you hold in your right hand but not in your left hand?
I travel in a gaggle.
No matter how little or how much you use me, you change me every month.