弄了大半天，人都麻了，看到两个博客参考了下，后面总算解决了。记录一下

1、选中左边一栏的第一句，插入脚注，主要要点右下角的一个小小的按键
2、插入脚注之后会空出一页，点击顶部菜单“文件，修改兼容性。

参考：
1、https://blog.csdn.net/qq_40538050/article/details/93721179?ops_request_misc=&request_id=&biz_id=102&utm_term=word%E4%B8%A4%E6%A0%8F%E6%80%8E%E4%B9%88%E6%8F%92%E5%85%A5%E8%84%9A%E6%B3%A8&utm_medium=distribute.pc_search_result.none-task-blog-2_allsobaiduweb~default-0-93721179.142^v73insert_down4,201^v4add_ask,239^v2insert_chatgpt&spm=1018.2226.3001.4187

2、https://blog.csdn.net/weixin_40185666/article/details/95046177?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522167827765116782427437956%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=167827765116782427437956&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2_allfirst_rank_ecpm_v1~rank_v31_ecpm-8-95046177-null-null.142^v73insert_down4,201^v4add_ask,239^v2insert_chatgpt&utm_term=word%E4%B8%A4%E6%A0%8F%E6%80%8E%E4%B9%88%E6%8F%92%E5%85%A5%E8%84%9A%E6%B3%A8&spm=1018.2226.3001.4187