After you have created your TOC, you will probably have to maintain it. The TOC is automatically updated whenever you open the document; but it's a good idea to also update it whenever you add more titles or headings in your document or when you add more content that may affect the page numbers that appear in the TOC. It's easy — just two steps.
You update the TOC by clicking the References tab and then Update Table in the Table of Contents group.
When you update the TOC, you will be asked if you want to update the entire TOC, or just the page numbers. Choose the page numbers option only if you've been adding body text but no new headings — it's faster and will save you time in a long document. But if you have added or changed a chapter title or heading, choose the Update entire table option.
Avoid editing entries in the TOC itself — if you ever update the TOC you will lose those changes. To change text that appears in the TOC, be sure to edit this text in the body of the document — not in the TOC — and then click Update Table to compile the changes.
Note It's also a good idea to update the TOC before printing or sending the document out; that way you will include any last-minute changes.