You connect two external monitors into a laptop that is running Windows 7 and Windows 8. When you try to extend or duplicate the desktop to the two external monitors in addition to the laptop screenusing the Win+P hot key option or from within the Display properties, either the changes do not take effect or you may receive the following error message:
Unable to save display settings
This error is most likely to occur when your laptop computer is configured with the laptop display and one of the two external monitors (Laptop Display + Monitor A) while in Extended mode, then you attempt to change the monitor configuration to Duplicate mode with the second external monitor (Laptop Display + Monitor B).
This issue occurs because some laptop graphic adapters only support two displays at one time. When you attempt to configure the display settings to use a third monitor on a laptop that supports only two monitors, Windows 7 and Windows 8 will check the hardware to confirm compatibility, then display the error message.
When you are using a laptop that is running Windows 7 and Windows 8 that supports only two monitors, configure the display settings to use only two displays at one time. Note:
You can also choose to disable the laptop screen, then use only the two external monitors.
When changing from Duplicate mode to Extended mode, you may note that this error message does not occur. This setting is designed to break up the Duplicate mode configuration prior to changing it to Extended mode.