OS X Yosemite: Arrangement pane of Displays preferences
If you connected one or more displays to your Mac, you can arrange your displays in any configuration in the Arrangement pane of Displays Preferences.
To open this pane, choose Apple menu > System Preferences, click Displays, then click Arrangement.
| Display graphic representation | Drag any of the displays to a different position. You can also drag the menu bar to any display. |
| Mirror Displays | Simultaneously show the same image on your Mac and all connected displays. |
| AirPlay Display | Use AirPlay Mirroring to wirelessly send what’s on your Mac to another display. |
| Show mirroring options in the menu bar when available | Show devices available for AirPlay Mirroring in the menu bar. |
| Gather Windows | Moves all open Displays preferences windows to the display showing this button. This button appears only if more than one display is connected to your Mac. |