Text, formatting, and style changes you make to a document's template (including the normal template) do not carry into already existing documents. You can go to the templates dialog and reattach your template checking the box to update styles. Apply the style, then go back and uncheck that box. It should not be left checked!
See
What is the relationship between a Microsoft Word document and its template? and
How do I copy content and settings from a template to a document?