Screen Settings & Projectors
You may have noticed that when you connect your Mac to a projector, two things usually/often happen:
Mirroring Madness
The settings default to non mirrored, that means the screen you see is not your desktop, it's using the projector as a second screen. This can be handy, but a simple fix is just to press command + F1 to switch mirroring on (or off).
Ridiculous Resolution
The size goes wonky, so everything looks too big, or you can't fit everything in, or the whole screen isn't used, and you have black bars on the sides of the screen—or all of these. The simple fix is to press option + F1 to bring up the display settings.
You can just pick a 'near enough' option like 1024 x 640, but it still won't look exactly right, but it is probably good enough. If you want to make it exactly right, you need to hold down the option key and click where it says Scaled now you can choose from a wider selection, for most of our college Epson projectors the size of 1280 x 720 should be fine.