Restrict the formatting to only those styles you approve. In the Protect Document task pane, under Formatting restrictions, select the Limit formatting to a selection of styles check box, and then click Settings.
When you restrict the formatting of your document, people can format text only with those styles you've approved for their use. In fact, most of the formatting tools (such as those on the Formatting toolbar) are unavailable when this restriction is in effect, and the Styles and Formatting task pane shows only the styles you've approved. This means no one can screw up those numbered or bulleted lists you worked on.
In the Formatting Restrictions dialog box, you can select the styles you want to make available for people to use. The Recommended Minimum option is generally the best one to choose, because it allows people to change some of the more commonly used styles, but it restricts changes to more complex styles.
Note When you apply formatting restrictions, they are in effect for everyone who can make changes to your document.