OK, thanks. I think I finally understand the rotation icons. They look like "portrait" and "landscape" (and the inversion of each), but they are actually rotations from the natural orientation of the device.
And the top menu Screen | Rotation menu are not arrows showing which way the screen will turn, but again are rotations from the natural orientation of the device.
I now have successfully set this up so it opens in portrait mode, and my docs will also open in portrait mode.
Thanks! (I knew I just wasn't understanding this.)
I have one PDF with very wide margins, and I was able to get KOReader to re-scale the view so that I have just the parts of the page I want in view. I haven't seen any other ebook or PDF reader that will do that.
Now I guess I need to work out how to run it on my Kobo Elipsa.
Thanks again.