How do I configure the programs that Konqueror uses to open different types of files?
In order to configure file associations, you should go to the KDE Control Center and choose the item File Associations under the category KDE Components. Suppose the default PDF viewer is now KGhostView and you would prefer to use KPDF as a viewer. You would simply type pdf in the search box at the top of the dialog, choose pdf in the application group and move KPDF up. In the Embedding tab you can also choose which component other applications will use to display files (for example, when viewing files in Konqueror or using Ark’s embedded viewer).