I have been using Ubuntu 13.10 for around 1 month and I haven't been able to make Ubuntu remember the configuration for my desktop background picture. Once I restart the system it goes back to the default background and the picture I chose simply disappears from the pictures' list in the configuration.
Actually, it's not the first issue with Ubuntu remembering configurations I've come across. Applications' sounds settings has the same problem, such as Skype.
Haven't found any solution to that yet, nor anyone with the same problem.