Extend Display will increase your workspace so that it extends onto the display. Selecting Mirror For with the name of the other screen will make macOS show the same image on both displays.

If you see the same thing on both displays, you should start by making sure the displays are Extended instead of Mirroring ...

Select "Second Screen" from the list of options. Click "Extend" to extend the space of your desktop across your two monitors. The settings automatically save.

If you’re completely new to monitors, there are two terms you need to know, resolution and refresh rate. Resolution refers to how many pixels a monitor can display and the most common are 720p ...

You've screen shared with a Mac mini connected to an HDTV but, by gum, that shared screen won't fill your computer's display. Chris Breen shows you how it's done.