title_body: Calibre changes font coverting AZW book to EPUB
upvoted_answer: You are best served to ask this in the Calibre Support forum on MobileRead.com.  Calibre author Kovid Goyal is an active participant.  See https://www.mobileread.com/forums/forumdisplay.php?f=166
  
  MobileRead is a privately funded site with free signup.  It's the single best site I am aware of for all things eBook.
  
  (Disclaimer: I am on staff and a moderator, thus biased. :-) )