this is stable way
in console run
sudo cp /usr/share/applications/gnome-appearance-properties.desktop /usr/share/gdm/autostart/LoginWindow
log out and change your settings. After second log in run command below. If you don’t run it you will see this settings screen always when log in.
sudo unlink /usr/share/gdm/autostart/LoginWindow/gnome-appearance-properties.desktop
sudo -u gdm dbus-launch gnome-appearance-properties
This opens the appearance configuration dialog, but for the welcome screen (GDM).
the most dangerous
Turn on PC, wait welcome screen. As soon as you will be prompted to select a user, press Ctrl+Alt+F1 to the command line. Log in as your user and run:
sudo -u gdm gnome-control-center
Ctrl+Alt+F7 for the graphic and you will see settings window. After all just close settings window.