You need to create a heading style just for an appendix. If your headings are numbered, you may not want the appendix heading numbered. I simply started from scratch. when you create the style, use Format-Paragraph-Outline Level to specify the level of the heading in the TOC. But do Format-Numbering-None to omit numbering. Or you could do these same things with a high-numbered heading style such as Heading 8.

Christopher Brewster
Lockheed Martin