1. Select [Style and Format] in [Format]. 2. The column "Style Format" appears on the right, mainly using the titles 1, 2 and 3. Title 1, title 2 and title 3 are applied to the titles of all chapters in the main text respectively. 3. Of course, the attributes of title 1, title 2 and title 3 (such as font size, center, bold, etc. ) you can modify it yourself. It's very convenient to define. Just point the cursor to "Chapter 1 Introduction to Refrigeration" and click the title 1 on the right with the left mouse button.