You must turn off the Link to Previous if you want a different footer in that section. If that action 'deletes' everything in the second footer then you just recreate it - is this different in your version of Word vs your earlier Word versions? You've ignored the information I put above about copying the footer contents BEFORE turning off the Link to Previous and then pasting it back in so you get what you get to some extent.

At its core, a page number is a field. You can insert that field in the footer by following these steps:
1. Type the word 'page' where you want the page number to appear (ie Section 2's footer)
2. Select this word and press Ctrl-F9 to make it a field and then press F9 to show the field result (ie the page number)

If the page number has started at 1 on the first page of that section, then that is all you need to do. If it has not:
3. While your cursor is somewhere in Section 2 (or its footer) go to Insert > Page Number > Format Page Numbers... to open the Page Number Format dialog
4. Choose the option to Start at 1 and click OK. If the number format is not in arabic numerals you may also want to set that is the same dialog.

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Andrew Lockton
Chrysalis Design, Melbourne Australia