To apply a style sheet to text using Edit > Find/Change (Cmd-F/Ctrl-F), uncheck Ignore Attributes on the Find/Change palette, enter a text string and/or choose character attributes on the Find What side of the palette, choose from the Style Sheet pop-up menu on the Change To side of the palette, then click the appropriate buttons at the bottom of the palette (see pages 290–294).
To use Find/Change to replace one style sheet with another on a case-by-case basis, choose both a Find What style sheet and a Change To style sheet. (If you were to delete and replace a style sheet in the Style Sheets dialog box instead, all occurrences of the style sheet would change.)