Increasing Top Document Margin un-obscures Header, but only for page 1.

I have a one row high header, and the header column(?) bar :… was covering the header (except when I click outside of the table). Apple support Add and remove headers and footers in Pages on Mac - Apple Support (AZ) … says:

"To set the distance from the top and bottom page margins, click the Document radio button in the toolbar, click the Document tab at the top of the sidebar, then click the arrows or enter values in the Top and Bottom fields (below the Header and Footer checkboxes)."

I increased the Top Document margin until the header on page 1 was no longer obscured, but on the following pages, the original problem persists. On that support page, there is also mention of Sections. I have not created any sections.

I thought that maybe I needed to click Documents & Margins | Facing Pages, so I tried that, but it has no effect on the issue, however after unselecting that option, my pages are now showing two across, and I'd like to have them show page 1, followed by page 2 below, etc. Bonus question: how can I return to that view?

(The Section tab has a section: "Headers & Footers", and I tried that, but it does not help (I realize that is about headers, and not Document Margins, but I thought I'd try it anyway.)

macOS 14.8.2

Pages version 14.4 (7043.0.93)