I tend to read my IPAD on the cross trainer at the gym. One annoying problem is that whenever you change pages in a PDF file, the zoom level I have set is lost and it reverts back to the default. Is there a way of setting the zoom level to remain constant across the pdf, so I do not have to refocus after changing a page? I have been using Ibooks, but will try others – although I prefer if alternatives are free. Thanks.