Documents will typically (and by default) be assembled into a new document using the "normal" template as the base. All styles, margins, headers and footers associated with the normal template will be active.
If you have a special template upon which you wish a certain Book to be assembled, note the name of the template in the Settings screen, under the templates tab. Read and see more at this link.
If you do not have a template in mind, but your clauses are not coming in with the correct style, you can easily create a template. Follow the steps outlined at this link and then associate it with a book using the above technique.