Fullscreen not working for mutliple display

Good day,

I have been building unity on window 7 and successfully run it on two monitors (2160 by 3840 and 1920 by 1080) on fullscreen mode. The application setting build are on fullscreen.

However, after switching to window10, only the later monitor (1920 by 1080) is able to present in full screen while the hi res monitor does not display the application in full screen. The splash screen on high res monitor used to be on fullscreen or maximized upon start for window7 OS but it is on windowed mode for window10 OS.

Is there any setting or additional function to add taht I need to handle for window 10 platform?

Can you show some screenshots? I’m entirely sure I understand your explanation.