A family of Microsoft word processing software products for creating web, email, and print documents.
By default, the table of contents is created with three levels, only. You can edit an existing TOC as follows: Press Alt+F9 (or Alt+Fn+F9 on some keyboards) to reveal field codes. You will see something similar to:
{ TOC \o "1-3" \h }
Delete the 3 and replace it with the number 5 instead. Press F9 (or Fn+F9) to update. If prompted, choose to update the whole table. Press Alt+F9 (Alt+Fn+F9) again to hide field codes and redisplay the TOC itself.