You can make the same kinds of changes to a slide layout that you make to a regular slide-for example, modify the appearance of text, change the slide background, and change the size of the images. If you want text, shapes, or images on a slide layout to be editable in your presentation, you must add them to the layout as placeholders. If you add new images, text, and other objects to a slide layout, these objects become part of the slide background and aren’t editable in your presentation. Only the slide in your presentation is changed the slide layout remains in its original state. Then you replace the placeholder elements and make other changes as necessary.
When you want to add a slide to your presentation that has particular elements-such as a title and subtitle, a bulleted list, or an image-you select the slide layout that most resembles the look and feel you want.
The slide templates used in each Keynote theme are based on slide layouts. Add and edit slide layouts in Keynote on Mac
