1, click Insert-Bookmark button;

2. In the opened dialog box, enter the book signature in the input box at the book signature, and click "Add";

3. Next time you open this document, click the Insert-Bookmark button, select the signature of the book in the opened dialog box, and click Locate, as shown in the figure.

Note: The book signature must start with a letter, and can contain numbers, but not spaces. You can use underscore characters to separate words.