By default, in Slide Show view you click your mouse to advance—or move—to the next slide. This setting is defined in the Transition to This Slide group on the Animations tab. You can modify this setting so each slide displays for a specific period of time before automatically advancing to the next slide. This is useful for unattended presentations, such as at a trade show booth.
You can also advance to the next slide by pressing the Enter key.
If you want to apply the same transition effect and timing for each slide, set the transition effect timing for one slide and click Apply to All.