Auto-applying a style in Word

You should be able to use the Find and Replace dialog to search for text with whatever attributes you're interested in and then use the advanced options to set the style of the replacement text (using the Format drop-down's Style option).

You can replace the found text with itself, so in effect you're just applying the style.

If you're going to need to do this multiple times, you could record it as a macro and play it back.

The Format Paint Tool can be double clicked to keep it active for multiple uses. You could copy the format that you want and apply it to the text on each page.

It's not nearly as elegant as creating a macro but it is significantly easier.

When you are finished press the ESC key to cancel the Format Paint Tool.