I am currently in the process of building an LFS system, and the LFS book comes in the format of a >300 page long PDF file. I am reading it via Ubuntu's default document viewer, and when I started I was able to scroll through the pages using my touchpad fine. Now, however, I can only scroll through the contents of one page, and must press N to get to the next page. I have restarted Document Viewer but to no avail.
How can I change this annoying functionality, so that I am able to scroll through as I normally would?