Instructions to change the default slide layout in PowerPoint:

1. Open the Slides Menu: go to the View menu, select Slide Sorter, and select the Slides tab.
2. Make Changes to the slide layout: click on each slide to select it, then go to the Format menu and select Slide Layout. Select the desired layout from the list of available slide layouts.
3. Save the Slides: go to the File menu and select Save to save the changes to the slide layout.