Welcome!

By the way, the whining kids do not like to be imitated. It annoys them if you whine just like them. They will see what they look like if you do it too. (talking about the 3 years old, not younger then this)

Sometimes positive reinforcement works better on certain kids. Remember that by saying "do not scream" you always works towards pushing the idea in. You reinforce the behavior instead of stopping it. So make sure you use words like "good you guys are talking softly today!" You get my point? (sorry not my first language so...)