If you want to change the page number format in section 1, then turn off
"same as previous" or "link to previous" in the header and footer of
section 2 before you modify the page number format in section 1.

If you want to change the page number format in, say, section 3, then
turn off "same as previous" or "link to previous" in the headers and
footers of sections 3 and 4 before you modify the page number format in
section 3.

There is a toggle button for "same as previous" or "link to previous" on
the Header and Footer toolbar that appears when you click on View |
Header and Footer.