You don’t need to be afraid of making mistakes in PowerPoint because you can use the Undo feature to erase your actions. The undo, redo, and repeat commands are very useful when working with text in a presentation.
Redo is the opposite of undo: it redoes an action you have undone. The Redo button appears only once you’ve used the Undo command. When Redo isn’t available, it is replaced by the Repeat button.
Click the Redo button.
Press Ctrl + Y.
The last action you undid is redone.
Once you've redone all the actions that were undone, the button changes back to the Repeat button.
Repeat is different from redo, because repeat applies the last command again. For example, rather than applying bold formatting by clicking the Bold button repeatedly, you can repeat the bold command with the Repeat button or keystroke.