This blog post describes how to set the header/footer in the format shown in Page X of Y in Word, so that it increases automatically with the number of pages. That is, set a different header for each page.
First add a header and choose a header style.
Then write in the header:
Page
Knock on it Ctrl+F9, and a pair of curly braces will appear:
Page { }
Fill in "PAGE" and type "of" outside the curly brackets:
Page { PAGE } of
Knock again Ctrl+F9and write "sectionpages" in the curly braces at the end
Page { PAGE } of { sectionpages }
To exit the header, press Alt+F9√ (sometimes press twice)