Two Features on the New Slide Button
The New Slide button is located at the left end of the Home Ribbon. It contains two separate feature buttons. The default slide layout for a new slide is the Title and Content type of slide.
If the currently selected slide is a Title slide, or if this will be the second slide added to the presentation, the default slide layout Title and Content type will be added.
Subsequent new slides will be added using the current slide type as a model. For example, if the current slide on screen was created using the Picture with Caption slide layout, the new slide will also be of that type.
The lower button will open the contextual menu showing the nine different slide layouts for you to choose from.