Press Windows key(between fn/ctrl & alt) + PPress both together, you will get projection settings popup on right side. Select EXTEND DISPLAY.Now your laptop should be Screen 1 & ext monitor Screen 2. If its the other way around, you can change that from settings.Pls mark as accepted if this solves your issue
7490, plug in external display into HDMI socket on laptop (HDMI both ends), external display repeats laptop display.  Say "detect", no display detected. Tested with other, different brand, monitor, no change.  I want a two screen display, not just a bigger screen   Ideas?
Using 7490 with dual monitor as spread display