The problem is that - rightly - debug and release configurations (including the settings file) are completely independent. If they weren't, then there would be a high risk of dev builds accessing production databases for example - which could be disastrous for the whole company.
There are ways round this, but they mean you handling the settings data yourself instead of relying on a settings file:
Where Should I Store My Data?[
^] That way, you can load / save the data and both dev and prod can access it.