I've had this problem before where the dual monitor setup would not be kept (i.e. I had my right screen as the main screen, but after restarting, the position of my right screen would be shifted to the left.), did a fresh reinstall and the problem got fixed (probably some other DE configs overriding each other since I had KDE, Gnome and Unity).
However, the problem now is that the dual monitor setup would be still broken on the login screen (my right screen would become the left one) and the screen config would only be fixed after I had logged in.
lightdmor some other display manager? – TheWanderer Oct 07 '16 at 01:13lightdm.conffile, onlylightdm-gtk-greeter.confandusers.confwith a emptylightdm.conf.dfolder. – dll Oct 07 '16 at 01:17lightdm.confanymore. I also found out that it was a known bug with Gnome. Gonna try and reinstall it. – dll Oct 15 '16 at 01:00