How to undo or redo a particular change?

You can undo or redo a change with the Undo and Redo icon buttons on the top of the right panel.

Or you can also use your keyboard shortcuts to achieve this:

To undo

Windows: Ctrl + Z

MacBook: CMD + Z

To redo

Windows: Ctrl + Y

MacBook: CMD + Y

Note: The redo button will only appear after you have undone a change