Editing a header in numbers that only appears when I print

In the past year I have transitioned from using a Microsoft laptop to an iPad and have imported several of my spreadsheets created in Excel into Numbers.

When printing one of these numbers documents (previously created in Excel) there is a header section with text that prints but I can’t see it when editing the document, it only shows up when in Print Preview and I can’t edit from there. Some of the info in that “hidden” header section has changed and needs to be updated, but I can’t seem to be able to access it to edit the text. I have watched YouTube videos, looked through several suggestions in numbers help and nothing seems to work. So checking here to see if anyone has any ideas or suggestions on how to get at that text to edit it?