To set a Heading, select the Zone designated as the Heading (Arrow 1), and from the Zone tab and choose Heading (Arrow 2) and the level (Arrow 3). You can also merge Headings with those from a previous page or zone, add line breaks to multi-line headings, and use the Heading structure as a template by checking any of the available, specified checkboxes. The template will only apply to this and subsequent pages. It will not apply to any previous pages.
Headings video.