COMPUTER FUNDAMENTALS

Detailed explanation-1: -To quickly undo the last change or two you have made to your image in Photoshop, using Control/Command + Z (or selecting Undo from the Edit menu) is fine. But when you need to make changes that go back more than a few steps, you want to look to the History Panel.

Detailed explanation-2: -1 Open the Undo History panel by choosing Window > Undo History. This panel keeps track of the last 50 actions that you have performed while the current file was open. The Undo History panel records the last 50 actions performed by default. The Undo History for a file is restarted every time the file is opened.