Captions only show when the page layout is set to Border or Square.
How do I add a caption on the web?
Log in to Chatbooks.com
Click Home at the top of the page, or click Account and then My Books
Click into the Chatbook you want to add captions to, then scroll down to see its pages
Click the photo you want to caption,
Looking under Page Options on the right side, click Caption
Type your caption, then click Save
Keep scrolling to add captions to other pages
How do I edit a caption?
Click the photo with the caption, update the text, and click Save.
Using the app? See How do I add a caption to my Monthbook?