How did you assign meaning to the bold text? In your screenshot, all I can see is formatted text, which appears to all be part of the same Binder item. Was this formatting applied through a Style? With text formatting commands?
A Section Layout can be used to format the title of an item, but it won’t do anything with subheads inside the item.
Either give the headers a style or split the document into smaller sections, cut the heading in each document, and paste it as the name of the new document. Give them a meaningful section type, create a layout for the text, assign the type to the layout, and format the text if necessary. Click to compile Titles, then go to the Formatting pane for the layout and format the text and title.