Are you using Firefox's built-in PDF viewer? It doesn't have all the features of the Adobe Acrobat plugin, so in that case, you may need to switch. This article has the steps for that: [[How to disable the built-in PDF viewer and use another viewer]]. Does that do what you need? There still may be links which the Adobe Acrobat plugin does not recognize, for example, if they are in images, or which are incomplete when broken by a line break. If there is an example document on line which is causing frustration, do you want to provide a link to it?