The major software change that Airbus has made is to hide info from the flight crew. It was too chatty and had too many important but deferable alert messages, including some that may affect the next flight but not the current one. So now they log it and send it but don't display it for the pilots to see, and this should improve the dispatch rate. Also a lot of the sensors are being detuned to be less sensitive (again to hide info). The original design assumed "perfect" real world conditions and now they have to deal with actual operating conditions (and things like water contamination of fuel).