2 Monitors

[Jesusfrk611]

Also you need to select your desired desktop configuration e.g. spanned, dual or cloned

I never had to do that to just extend the desktop... I just selected the desktop that wasn't active in the settings and clicked "Extend my Windows desktop onto this monitor"

Screenshot:

Although I have 3, not just 2.

 

[A True Folder]

Does your taskbar run along the bottom of all three monitors??

I've not run three monitors so it maybe the third monitor alters the options.