First. Read the link.
What is the difference between headings and headers?

When you report back that you have done so, let me know.
I know, I'm finicky. I'm also old and a bit grumpy.

These terms matter and using the wrong term willl make it much harder for you to get help, here or in Word's help. It is obvious to me that you are talking about headings and not headers. It may not be obvious to others and when you search by the term "header" you get much different information than you do for "heading."

(BTW: The other links I gave you would help you understand this better. Despite MS's efforts to convince us otherwise, Word is a fairly complex program.)