I have just installed a new printer on my system. Firefox used the old printer name by default
Following the advice in: http://support.mozilla.org/en-US/questions/762570#answer-114800
I have printed a number of documents using the new printer (Firefox is supposed to remember the name of the last printer used) -- no change;
Reset the value field in about:config->print.print_printer -- the entire entry has disappeared and has not been restored after printing a document; also the default printer is not changed
Abolished my old printer -- Firefox now defaults to a virtual printer, namely Cups-PDF
Set the value field in print.save_print_settings to false -- Firefox still uses Cups-PDF
The new printer, once selected, works perfectly.
What's going on? How can I change the default printer to the value I want?
I am not sure what you have done; but could you have you left the preferences in for the old printer and so Firefox is defaulting to printing to file, (those preferences will end print_to_filename) because there are no entries for the new printer.
You could try resetting the print settings by resetting the pref print.print_printer or you could follow the instructions in the above linked article and manually reset all printer preferences by editing prefs.js to delete all the print preferences. (Back it up first by copying it, and work with Firefox closed down)
I don't think printing is a strongpoint of Firefox.
For added weirdness, immediately after selecting "Print" the default printer, "Cups-PDF" is greyed out, and the Print button is inactive. After selecting another printer, say "Print to File", "Cups-PDF" becomes active.
I had the same problem with cups-pdf being the default printer (even though it wasn't at server level) but it wasn't related only to Firefox but to each and every program that printed through CUPS, even KDE. I finally solved it opening the file ~/.cups/lpoptions and deleting the line that said "Default PDF". That's all!