This is due to "Intel Graphics and Media control panel" software setting, you can follow the instruction below: 

1. Right click on desktop and choose [Graphic Properties].
    

2. Select [Advanced Mode] > [OK].
   

3. Click [Display] > [General Settings] > [Display] and choose your monitor accordingly. Thereafter, set [Scaling] to [Customize Aspect Ratio] and make both  [Horizontal Scaling] and [Vertical Scaling] to 100%. Click [OK] to finalize the procedure.