I'm curious. What changes were made to prevent an AF 447 accident from happening again?

The good thing about flying a Boeing, MD, Embraer, or Bombardier aircraft is that you don't have to worry about which "flight mode" you are operating under. The FO on AF 447 was doing as he was trained. Under normal operation on an Airbus all you have to do is pull back on the side-stick and the computer will take care of other factors such as engine thrust and climb angle. So, the FO saw they were descending and pulled back on the side-stick to climb. He thought the Airbus would take care of the rest. He didn't realize that the aircraft was in an alternate flight mode which requires manual inputs. He continued to pitch up and put the aircraft into unrecoverable situation. The pilots were under the false assumption that their Airbus was incapable of stalling and falling out of the sky.

When Airbus released their first flight-envelope protection aircraft (A320) they misled the world into thinking the aircraft would never let itself enter dangerous territory. Similar to how White Star Line touted the Titanic as unsinkable. Never say never.