You can add and edit the captions on each page of the photobook from the edit page by clicking on it and typing or editing the text in the text box. You can customize the text by choosing from the different fonts and colors available.

In the photo book, you can't add custom text to every page of your book. However, you can automatically add the date, location, and captions for your uploaded photos by clicking "Show text" next to the front of the book on the edit page.