Google Slides has built-in slides, to which users can add their designs. Google Slide users can change the font, font color, and background of the Slide. They can also change the theme of the slide.
To edit a footer in your PowerPoint slides and include citations or notes, you'll need to access the Header & Footer menu ...
You can add page numbers to your PowerPoint slideshow through the "Slide Master" page, which lets you edit your entire slideshow at once.