How do I undo or redo a change in my design?

To undo/redo a change in your design, you have two options:

Option 1: Use keyboard shortcuts

Mac OSx Keyboard Shortcuts:
Undo action: Command + Z
Redo action: Command + Y

Windows keyboard shortcuts:
Undo action: Control + Z
Redo action: Control + Y

Option 2: Click the undo / redo buttons