Black bars on external display I am connecting my 2015 MacBook Air 13" to an external display via the Thunderbolt-to-VGA adapter.  There are black bars on each side of the external display screen.  How can I remove the bars? 


Macbook Air 13" (Early 2015)
LG Flatron E2360
Dell Thunderbolt to VGA Adapter.
The vertical black bars appear when the MacBook screen resolution and the external display screen resolution is not in the same ratio. 

To fix that, when you connect to the screen, there is a prompt to choose which screen resolution you want to use. It’s either MacBook or the external display. This is how vanilla MacOS works. 

Or, go Apple Menu --> System Preferences -->  "Displays" pane  set your preferred monitor resolutions there.