: View the formatting palatte (Menu: View/Formatting Palatte)
: Pull down the styles list
: Pick an existing style to change by pressing the blue paragraph marker
: to right. Then press "modify" button.
: Or press the "new" button to create a new style
For such a major and hopefully lucrative project, you might be well
served to pay for someone to come in a give you a 2-4 hour coaching
session about how to write with Word. They can explain all this, setup
some bespoke templates or template, show you how manage them.
Alternatively, buy a book about Word. I don't know what's available on
Mac, but I know there are a lot on Word for Windows and the principles
are the same.
Styles and Templates are at the very *heart* of using Word so that it
become a real writing tool with real benefits. No author using Word
should avoid them.