After update to xfce4-settings 4.13.6 display settings doesn't last over reboot/relogin.
As stated in bug 15416 comment 3, settings are applied to current session, but are reverted back previous values after reboot/relogin.
Looks like new settings are preserved over reboot/relogin only if a new profile is created. Previously I had no profiles available.
*** This bug has been marked as a duplicate of bug 15437 ***