Clicking on the "Change" (German: "Wechseln") Button in presenter console swaps primary and secondary monitor - but only once. By no means can this change be reverted. Clicking the button more than once only changes back as long as the button is clicked but swaps back to Presenter Console on secondary monitor immediately. Even after closing the presentation, exiting and restarting Impress the presenter console view displays on the secondary display as soon as the presentation is started.
This bug happens with XFCE / Xubuntu 16.04. I am using ARandR to set the screen layouts. Even changing the layout on ARandR doesn't allow to revert back to the presenter console displaying on the primary monitor.
Only removing the VGA cable, resetting the sceen layouts with ARandR, then reconnecting the VGA and setting the dual screen anew fixes the problem. Apearently Impress messes up the screen settings.
It seems Xfce is problematic with presenter console: bug 102500
Have you reported your problem to Xfce?
Set to NEEDINFO.
Change back to UNCONFIRMED after you have provided the information.
Raised the issue on XFCE bugzilla as bug 12893