Okay thanks. I see the problem now: I changed from A4 portrait to A0 landscape but there was no indication of a size change with Apple's dodgy half-the-time-hidden scroll bars that drive many people nuts. It looked as if there had been no change whatever page sizes I choose. So it tried ⌘ + "—&...
Maybe this is the answer that gets the buzzer if this was QI but he goes, why not Adobe InDesign? All that you request and much, much more. Subscription pricing so you can use it and leave after one or two months, or if its a years work get cheaper monthly pricing.
So i searched the PDF contents, read quite a few sections and search "page" "Page size" and "board" but coming up blanks… Tell me it isn't so. Changing page size to custom A1/A2 whatever page size doesn't change anything at all which is against the flow of every Mac app...