A family of Microsoft word processing software products for creating web, email, and print documents.
I was hoping there was a way to apply the new template to reformat the existing document.
You didn't read far enough down that article. In Section 2.7 "Styles" is this information:
You can update the document with its template's styles. To do that:
...
- In Word 2007 and Word 2010 [and later]: Developer > Document Template; tick the Automatically Update Document Styles box
Having ticked that box, immediately go back and un-tick that box. Don't leave the box ticked.
This updates the definition of each style in the document to match the same-named style in the template. That changes all of the things that are part of the styles: font (including size, color, etc.) and paragraph settings (line spacing, above/below spacing, indents, alignment, etc.). These changes take effect immediately.
If there are headers/footers in the template, you'll have to copy/paste those from the template to the document -- they aren't part of a style. I suspect the document's margins, orientation, and page size won't change automatically either, as those are section properties and not part of a style.
Since the new template is now "attached" to the document, any customizations stored in the template (building blocks, keyboard shortcuts, template-specific Quick Access Toolbar commands) are available.