Configuring the Pages Pane
http://www.planetpdf.com/enterprise/article.asp?ContentID=6115

Baker, Donna L.
PlanetPDF
2001

Abstract:

The default layout of the Pages pane displays a single column of small thumbnail pictures of the pages. The default is fine for most kinds of work when you have a document consisting of several pages. However, when working with a very large document, you might want to make the thumbnails smaller and increase the number of thumbnail columns to see more at once. If you have to be able to see the content of the thumbnails, you'll want to increase their size.