On both our Windows and Linux machines, the monitor arrangement can be adjusted by end users.
Windows:
The monitor arrangement setting is available by going to "Display" settings either by going to Settings -> System -> Display or by right clicking on the desktop and selecting "Display settings". This setting on windows is a machine setting so once set by a user it affects all other users so please be courtious and keep changes reasonable or change them back before logging off.
Linux:
On Linux, in addition to desktop environment specific tools, the display arrangement can be modified using "xrandr" and "arandr". Most users will find lauching "arandr" from any terminal window and then adjusting the displays using a drag & drop GUI the easiest method.
xrandr is a command line application suited for "advanced" users wishing to automate their display arrangement using scripts.