Epson Projector Only Displays Background Picture

What to do when you can't see windows or your menu bar on the image projected by your Epson (or other brand) projector.

Problem

Epson projector is only displaying your computer desktop but you can't see your windows or menu bar.

Solution for macOS

Instructions based on macOS "Ventura" (13.2)

You need to have the computer plugged into the projector then go to  → System Settings → Displays → "Arrange..." button. Follow the onscreen instructions as pictured below.

macOS 13.2's "arrange displays" system setting. Test in window reads, "to rearrange displays, drag them to the desired position. To mirror displays, hold option while dragging them on top of each other. To relocate the menu bar, drag it to a different display."

Note: If you are on macOS 12 or lower, you will go to  → System Preferences → Display, and check the "Mirror Displays" as pictured below.

OS X display preference panel
macOS 10.12 screenshot

Solution for Windows 10

Press and hold the Windows key (flag icon on keyboard) then press P (think Projector). You'll get the following on your screen:

Windows 10 display settings screenshot

Windows 10 screenshot

Choose Duplicate option instead of Extend and your projector will show what is on your screen instead of the blank background image.