Have you viewed the document with hidden characters displayed? That will allow you to see section breaks. I suspect that there are lots of them; perhaps someone "carefully" inserted them when pasting in material from other documents.

Footers are a section characteristic. Your page umbers may be autonumbered, simply typed in, or (my guess), a combination of both. In any case, autonumbered page numbers (i.e., fields) pertain to a section at a time.

Unless there is some reason not to, e.g., multiple columns on some pages, I would see if you can eliminate the section breaks. Once done, setting the page numbering using Words page numbering should make life fairly simple.

Does this help?