Changing the date is easy. Just call whoever issued the ticket and have a new reservation made. As far as changing the destination, there are more restrictions. You can do it for $75, but if it;s your last segment then you are more limited. If you are ending in Paris, I can only assume you started the trip in France. That means that you still have to end the trip in France. So you can change the destination for $75 but only to a destination in France.