As you work on a presentation, you take some actions that are general, or repetitive, and that don't have to do with a particular phase of the process, such as saving your file or undoing something you didn't mean to do.
For such things, use the Quick Access Toolbar. It's the small group of buttons on the left, above the Ribbon. It contains the Save, Undo, and Repeat or Redo commands.
Play the animation to see how you can add other buttons to the toolbar, and how you can remove them.