I am working with a template in Word, and if I apply a style to a paragraph and then manually change a characteristic about that paragraph (for example, make it bold), Word automatically creates a new style in the template called "style name + bold". How can I stop Word from automatically creating these extraneous, on-the-fly styles?

Related question: Can I "lock" a template so that the styles I created in it cannot be inadvertently changed, but a user can still apply manual formatting to selected text in a document using that template?