Acrobat 2020 editing the Header or Footer in a PDF Document

I use Acrobat 2020 (pro) to edit a large document. When I insert a “Header” I can use the tool to edit “headers and footers” like in a Word Document.
https://www.adobe.com/au/acrobat/hub/how-to/how-to-use-headers-footers-in-pdfs.html
I have to do this because the document is puzzled of 100 different documents and is printed at the end.
The header contains a Page-Number and when I update the header, Acrobat will find the pagenumbers in all this textboxes and update the numbers (or text).
Now, I will find this pagenumbers in the document and a textbox nearby. Is there anybody who knows how to do this? Acrobat will find it, then eg VBA or Java Script will find it too.
But how?