In fiddling wih this, remember, UnDo (Ctrl+Z) is your friend.

When you delete the section break, everything will have the formatting you applied in the last section. Again, I suspect you changed your margin in the last section. Deleting the section break will make that margin setting apply to section 2.

Changing the link to previous setting in the header/footer will let you make changes in them in one section without changing the rest.