Aperture Change slideshow settings
You can change the settings that determine how your slideshow looks and plays. For example, you can set the aspect ratio for the slideshow, change the background color, set the length of time slides appear, and add titles, transitions, and effects.
You can change settings for the entire slideshow or for individual slides. You change settings for the entire slideshow in the Default Settings pane of the Slideshow Editor, and you change settings for individual slides in the Selected Slides pane.
Important: The settings available for a slideshow depend on the theme you choose. The Classic and Ken Burns themes are the most customizable. For information about changing the slideshow theme, see Create a slideshow and choose a theme.
Modify settings for the entire slideshow
Select a slideshow album in the Library inspector.
Click the Slideshow Settings button
in the lower-right corner of the Slideshow Editor, and click the Default Settings button.
In the Default Settings pane, change the settings for your slideshow.
Modify individual slides
Select a slideshow album in the Library inspector.
Select photos in the Browser.
Click the Slideshow Settings button
in the lower-right corner of the Slideshow Editor, and click the Selected Slides button.
In the Selected Slides pane, modify settings for the selected photos.