Symptoms
In Windows 8 or Windows 8.1, if you change the display resolution or DPI, some items such as the Start screen may not change until you reboot.
Cause
In Windows 7, you were forced to reboot to apply all the changes. In Windows 8 and 8.1, you are not forced to reboot. If you don't, the display changes may not be applied to all items on the screen.
Resolution
Reboot the device after changing resolution settings.