I cannot give you details as I'm not sure of the exact steps you need to perform. However, so far you've altered how calibre deals with it's own
internal information. Not how calibre
exports information.
You are going to need to look at the Send to Disk, or Send to Device output in the Preferences. Something in the output rules needs to be changed to produce the expected output. Since I'm reading ebooks on my PC, I cannot advise you further. Take a look through the
Calibre User Manual for more information.
If that doesn't work you might have to create a custom Template or Plugboard; which are advanced features - but I think that should not be necessary.