Setting primary display on a dual display setup

[galapogos]

Hi,

I have 2 monitors on a dual display setup - one connected via VGA and another connected via DVI. Right now CentOS thinks the VGA one is the primary, but I want the DVI one to be primary. How do I do that?

Thanks.

[pvanos]

As I experienced the same problem, but no answer was yet given:
You may have to install xrandr first.
Then :
xrandr --> shows a list of the display names detected. One of them is marked as 'connected primary'.
In my case it returned :

• VGA1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 477mm x 268mm
  HDMI1 connected 1680x1050+1929+0 (normal left inverted right x axis y axis) 474mm x 296mm

xrandr --output HDMI1 --primary
The primary display changes instantly.

[pvanos]

Today, I found out it's even far more easy when using GNOME :
System Tools -> Settings -> (Hardware) Displays
You will notice 2 displays, each identified with a different colour.
On top of one of them, there is a little black bar.
Just drag it to the other screen, and hit [Apply]

Done!