I know Yamaha manuals often aint that good, but the functions of those switches should be well covered in the quick start guides and manual for the mixer. Mixers especially normally have good documentation (a signal routing diagram if nothing else) as people like to understand the internal audio routing options etc.
It might even recomend a normal setup for the monitoring as well, along with what channels at the computer end of the USB do what, and how to set them up in cubase.
If after reading through that you dont understand the terms - then by all means ask, but first port of call for information about using you gear should really be the manuals that come with it, and your post suggest that they are in need of a first read
