Top setup vent so that everyone comes in at the same volume do the fiollowing
Go to Setup
Enable Direct Sound
Select the SFX Button
Select Compressor and click Add.
Under Compressor Properties use the following settings:
Gain = Adjust for how loud you want people to be. (I use 15)
Attack = 0.01
Release = Around 500
Threshold = Around -30
Ratio = 100
Pre delay = 4.0
Done!
This stops one person shouting and increases the sound of those who are quiet