Page Numbers, in Word, are fields. They are never something that you type. You insert the field.

• Page Numbers in Word 2007-2021 (365)
• Pagination Fields
• Dealing with Fields in Microsoft Word

Every Section in Word has three footers and three headers, whether or not you see them. Header/Footer, First Page H/F, Even Page H/F. These are discrete parts of the section and have nothing to do with link to previous. Link to Previous can connect a header or footer of one type to the one of the same type in the previous section.

So if you are using more than one of these types, you have to repeat the same content in each header or footer you are using in a section. The First-Page header is a different header from the "Header" (or the "Odd-Page Header") or the "Even-Page Header."

• Header/Footer Settings Recap
• When to use Section breaks in Microsoft Word (and when to not use Section Breaks)