Go to the end of the document and choose View - Header and Footer. There is
a tool in the right half of the Header and Footer toolbar that says Link to
Previous. If it's not dimmed (i.e., if it looks pushed-in), then that means
that the Header/Footer for this section is already the same as the previous
section. Once it's turned on, click the Show Previous button. (You should be
prompted to delete the header/footer and connect to the header/footer in the
previous section.)
Alternate between setting each section to Link to Previous and Show Previous
until all document sections have the same header/footer. Another thing to
check is File - Page Setup - Layout tab, and make sure that Different Odd
and Even and Different First Page are set up as you want them to be.