How do I control each mono instance of the Liquid Mix, from the plug-in window?
You can control every instance from the software GUI or from the desktop hardware, depending on your preference; each has its benefits. The software shows all control settings simultaneously whereas the hardware allows tactile, hands-on control. The hardware is arguably the quickest as you can easily switch from one track in your session to another, but the GUI has clearer graphical display and metering.