Go back to one page in portrait rather than two in landscape

My documents suddenly open in landscape, with two pages side by side. I want only one page to show at a time, scrolling down to view subsequent pages in a document. Following the help advice, I went to Format>Page> but the default settings are already for portrait, letter style, one column. Advice would be appreciated as to why the page orientation changed and how to get back to what I want?

There are three small icons on the Status bar at the bottom right of LibreOffice window. Try clicking the leftmost one (looks like a single page) and change the slider to their right to get a nice scale.

That was it! Thank you very much.