Keynote for Mac: Change the layout or theme of Keynote slides
Every Keynote theme includes different master slide layouts. To quickly change the look of a slide, you can apply a different master to it. You can also turn body text and title placeholders off to hide them on a slide.
You can also choose a different theme for the presentation.
Apply a different master to a slide
Reapply a master to a slide
You can reapply a master to a slide so that text and media placeholders return to their default style and position, the slide background returns to its default color or image, and placeholder objects are shown or hidden as they were by default.
Note: If you’re sharing a presentation with others, you can’t reapply master slides.
Show or hide title and body text placeholders
Change the slide size
You can change the slide size to fit screens with different aspect ratios.
Note: You can’t change the slide size of a presentation you’re sharing with others.
In the Document sidebar, click the pop-up menu below Slide Size and choose a new size. If you choose Custom Slide Size, enter slide dimensions, then click OK.
Change the presentation theme
You can change the theme of a presentation at any time. Your existing slides inherit the attributes of the new theme, including object styles, title styles, and more. If you customized anything on your slides—for example, if you changed slide backgrounds or the color of text—you can choose to retain those changes.
Note: You can’t change the theme of a presentation you’re sharing with others.
Choose File > Change Theme (from the File menu at the top of your screen), then select a new theme.
Deselect the “Keep your style changes” checkbox if you want the new theme styles to override your style changes.