I understand your frustration. I've been there.

However, had you followed those steps, all of them, in order, you would not be having this problem because the styles would take care of it.

In a heavily-edited document Word's automatic numbering is FUBAR unless the numbering is properly linked to styles. The reasons for this are explained in John McGhie's article Word Numbering Explained. Shauna Kelly's work is based on that article. Reading it may give you context for the reasons for the steps.

Numbering in Microsoft Word

I, too, invite you to post a version of the problem document. To post a document here you need to click the "Go Advanced" button at the bottom of the reply window and then click on the paperclip attachment button.

You can fill the document with non-confidential text using the Rand or Lorem autocorrect functions. The rand "virus": or how to insert dummy text into a document