HDMI display behavior on startup I have a display connected to the HDMI port of my laptop. When I start up the computer with the display plugged in, the built-in display does not turn on, and the external display becomes the primary. I can fix the issue by removing and reconnecting the HDMI cable, but I am curious as to why this behavior is the default.


OS 10.10.4
MacBook Pro Retina 15" mid 2015 (model 11,5)
It sounds like you have the external display set as the primary display.  Take a look at this article on how to set your primary display.

Set the Primary Display on a Mac