The Collapse All and Expand All buttons are located beneath the Collapse and Expand buttons on the Outlining toolbar. When you click the Collapse All button, PowerPoint collapses the entire outline so only the slide titles show. If you collapse the entire outline using the Collapse All Toolbar button, click the Expand All button to later restore the outline.
The Summary Slide button is the second to the last button on the Outlining toolbar. When you click the Summary Slide button, PowerPoint adds a summary slide to your outline. To use this toolbar button, position the insertion point at the very end of your outline and then click the Summary Slide button so that your Summary Slide is added to the end of your presentation.