There is no exchange of setting between versions, they are independant.
CS6 should set its file associations automatically. You can try pressing the radio button to "reset to default associations".
If you uninstalled CS5 after you installed CS6 you may have corrupted your file associations.
thanks but I'm not talking about what files bridge opens when you open from whithin bridge but what files open in bridge when you open from explorer
Then that would be controlled by the OS file association settings.