If you want to undo something on your macbook, there are a few different ways that you can do so. Depending on what you want to undo, you may be able to use the undo command, or you may need to use a different method.
If you want to undo an action that you just took, you can press Command-Z on your keyboard. This will undo the last action that you took. If you want to redo an action, you can press Command-Shift-Z.
If you want to undo an action that you took a while ago, you can use the Time Machine feature. To do this, open the Time Machine preferences and select the "Show Time Machine in menu bar" option. Then, you can click the Time Machine icon in the menu bar and select "Enter Time Machine." This will take you back to the point in time when you last saved your file. From there, you can navigate to the point before you made the change that you want to undo, and then click "Restore."
If you want to undo a change that you made to a file, you can use the Version history feature in the Finder. To do this, right-click on the file and select "Get info." Under the "General" section, you will see a "Version history" section. From here, you can click on the version of the file that you want to restore, and then click the "Restore" button.