For those of us that like to tweak things and customize, sometimes we must reload the desktop in order to see the changes. Logging out and in or even rebooting can make that tedious.
On Zorin OS Core (Gnome):
Tap alt+F2 and enter into the prompt:
r and hit the enter key. That will refresh Gnome-Shell / Desktop
On Zorin OS Lite:
Tap ctrl+alt+esc and then left-click and open area of the desktop. The effect is immediate and the desktop is refreshed.
On Zorin OS using Cinnamon (For those of us who installed it):
Same as Core:
r and enter key.