I had an issue a while back where the primary display in the monitor control panel did not match the position in Carrara preferences for some reason.

From your screenshot, it appears Carrara is expecting the primary display as the left display. If you check your monitor control panel, be sure the the primary monitor is also configured as the left display.

Note that I am NOT referring to the physical location of the monitor.

If the primary monitor is also on the left in the control panel, then try switching it to the right and reopen Carrara and check the Prefs to see if anything has changed.

I think I had to reinstall the the display drivers when this got screwed up on my system.