Here are some steps to diagnose why your headers and footers are not the same on each page:

1. Check that your margins are consistent in your document settings
2. Check that your header/footer style is being properly applied to each page
3. Check that the units of measurement (e.g. points, inches) you are using to measure page/header/footer sizes match
4. Check that the settings you have applied are properly applied to the current section
5. If your document contains multiple sections, check that the settings you have provided are being properly applied to each section
6. Check that any non-default page formatting is properly reflected in the headers and footers