Auto Size mode causes the Title tool to add or remove pages automatically as you add, delete, or reformat the text. You can disable Auto Size mode, for example, if you want to add extra pages before or after the text to make room for additional title elements.
Auto Size mode is active by default in Rolling and Crawling Title mode.
For more information on adding extra pages with Auto Size mode disabled, see
Adding Pages in a Rolling or Crawling Title.
A check mark indicates that Auto Size mode is enabled.