It is always the simple things that seem to annoy. I’m still using Lucid (10.04) quite happily but was unhappy with the PDF reader. I discovered that Foxit (my widows preferred reader) does have a Linux version though it seems it has not been updated since 09. No bother, I downloaded the dep package from here and it installed and worked no problem. However, Nautilus would not change it to be the default program. The solution turned out to be very simple.
Open ~/.local/share/applications/mimeapps.list in gedit. You will see a line
I have already changed the order of applications here so Foxit is first choice. Simple really…