Photoshop allows only 1 undo and redo for any given modification.
Although this unique ‘undo/redo’ will appear at first to be rather ineffective for our workflow, it does allow us to quickly see difference between two version of our image, such as in the case of a subtle tone or colour balance change. Besides, one can easily use the History Panel, like we described in this article, in order to go back several steps.
The undo/redo function is done using a hotkey, or a key combination for quick results. The undo/redo hotkey is Command + Z on a Mac or Control + Z on a PC. Of course, this function is also available through the Edit menu; it will be the very first one on top of the menu list in both the case of the Undo and the Redo, depending at which point you are in your workflow.
For multiple undo options, you can explore the History panel to which instructionsare given in our article entitled How to undo in Photoshop.