PowerPoint 2016 for Windows expects you first to make a selection, and then the do something such as clicking a button to perform an action for the selected slide objects. If you cannot select an object, then you cannot modify it at all. Although this tutorial explains how you can select shapes on a slide, the process works the same way for any other slide object.
Learn how to select and deselect single and multiple shapes in PowerPoint 2016 for Windows.

