Oltre alla risposta corretta di @ cmason, potresti trovare vantaggioso rivedere il "Nozioni di base su Mac - Visitare il Mac Interface ".
Più in particolare riguardo alle app a schermo intero, troverai ulteriori informazioni qui: OS X Yosemite: porta le app a schermo intero.
Estratto:
Return to standard view: Move the pointer to the top-left corner of
the screen, then click the green full-screen button again, or press
Control-Command (⌘)-F.
Un altro:
OS X Yosemite: Window basics
Switch to full screen In many apps, including Calendar and Mail, you
can expand the window to fill your entire screen.
Click the green full-screen button in the top-left corner of an app
window.
Button for entering full screen Return to standard view by moving the
pointer to the top-left corner of the screen, then clicking the green
full-screen button again.