I don't understand what you don't understand. Looking at the footers, there are two sections Word thinks is there but don't appear on a selection list.
When I choose Insert->Page Numbers->Format Page Numbers,
the window that appears has a feature where you can pick which section you would like
this formatting to apply to. Sections 1-9 are available for selection, Sections 10 and 11 are not on the list.

Therefore, they never get the formatting right for the page number. The links you sent do not address this question.