I have a laptop running Xubunu 12.10 with an HDMI display attached. When I log off or reboot, and then log back in, I need to reapply my display arrangements in ARandR when I log back in (oddly, the resolutions are maintained, but not the placement). My display arrangements also break when an HDMI switch is used. What can I do to fix this?
I had the same problem: XUbuntu 12.10, two monitors, and I had to reset my screen layout with ARandR each time I logged in. By default it wanted to "mirror" the displays.
I configured the monitors the way I wanted them in ARandR and saved a single layout in ARandR, dual_monitor.sh. ("Layout | Save As" from the ARandR menu.) The file went to /home/user/.screenlayout/dual_monitor.sh. I was pleasantly surprised to discover that was all I had to do. With no further adjustments I logged out, logged back in, and the two monitor configuration was in place.
I have no answer to the HDMI switch portion of the question.