settings changed - 3 monitors - maximises window across all 3 monitors instead of 1

Hi,

I have been using 4 monitorsby adding three 22inch monitors to my laptop
with a graphics expansion module and have not had the problem below until
this time.

* SETUP :
1 Laptop
1 Graphics Expansion Module with three 22inch monitors attached


* What Happened :
I detached the USB plug to the Graphics Expansion Module and the VGA cable,
EITHER after unclicking the "extend the desktop to the this monitor" option,
OR i unplugged both cables while the laptop was off,
and re-attched them after restarting it later.And extended the desktop and
chose option to use the 3 monitors attached to the Graphics Expansion Module
as the "Primary Display".

BUT when i re-attached both cables,a window popped up (which happens only
sometimes after i re-attach the cables),i missed out on clicking the option
of expanding the desktop and not cloning the desktop. i dont think this is
even the cause of the problem below,I think it is some other setting that
has changed after detaching and reattaching the cables.

I have tried to detach and reattach the cables so that popup window will
appear,to choose whether to clone or extend my desktop but it wont appear (i
dont think this is the problem anyway).


* PROBLEM :
Now when i maximise any window on any one of the three 22inch monitors
(attached to the graphics expansion module), it opens that window across ALL
THREE MONITORS RATHER THAN JUST THE ONE MONITOR THAT MOST OF THAT WINDOW IS
APPEARING IN.
I have never had this problem before.
And i cannot find the setting to change it back -so that when i maximise a
window it will maximise only on ONE monitor that most of that window is
appearing in,rather than all three of the monitors attached to the graphics
expansion module.
This happens whether the Laptop Monitor or the Graphics Expansion Module is
the "Primary" Display.

HOW do i change it back ????

Does anyone know ????

Thanks very much