When I am scrolling on a PDF document, sometimes I can scroll line by line, even when page is changing ie I can view sections of both pages on screen. While some times, when page changes, the new page occupies entire screen. I can not keep few lines from existing page and few lines from next page on the screen. Why is that, if I want to maintain sections from both pages on same screen, how can I do that ?
It's related to your view preferences. Unless you specify a specific view, the settings in the PDF file will be in effect.
Try this: Go to Edit - Preferences - Page Display, and under "Page Layout" select "Single Page Continuous".