Undo is one of the most important tools in Photoshop, and knowing how to use it can save you a lot of time. Here are five tips for increasing your undo abilities:

  1. Use keyboard shortcuts. Many of Photoshop’s most common commands are available as keyboard shortcuts, so take advantage of them whenever possible. For example, pressing Ctrl+Z (Windows) or Command+Z (Mac) will undo the last action you performed.
  2. Use the History panel. The History panel is a great way to track your progress through a document. It stores all the changes you’ve made so far, so you can go back and make changes if necessary.
  3. Use the Undo command frequently. The Undo command is located in the Edit menu (Windows) or the Command menu (Mac). Use it to go back and fix mistakes quickly and easily.
  4. Keep an eye on your history buffer size. The history buffer size is how many changes Photoshop can store at once; as your document gets larger, the history buffer size will need to be increased in order for Undo to work properly.
  5. Experiment with different techniques and settings until you find what works best for you." ..