Ever since I went into recovery mode to repair my disk since upgrading to yosemite, my computer mirrors the login screen to my external display. Something it wasn't doing before even on yosemite. I tried resetting PRAM but that does nothing. It's especially annoying because it adapts to the screen size of the external display. Any tips? Also, while on login screen, when unplugging and re plugging in display, settings while revert to normal.