We have a produced a series of short videos that introduce the general concepts of multi-monitor setups in Windows, how to make changes to the way things behave, as well as how to solve common problems. 

Direct links to the introductory videos our customers have found the most useful are:

Introduction to multiple displays in Windows

Common multi-monitor problem – spatial orientation

How to make a display the ‘Main’ display in Windows

Multi-monitor problem – spatial orientation part two

Introduction to display scaling in Windows

We also maintain a 'playlist' that contains all of the multiple monitor tutorial videos we have made available here --> Link