How do I change the language for all aplication under Ubuntu 11.04 ?

[Pop Horea-Vasile]

Hello,
my name is Horea and I'm from Romania.
At OS install process I've chosed RO but now want to change to EN 
(language).
I've selected only EN at Language Support and pressed the system wide 
button but there are aplications that are still in romanian.
I know a mettod that consist in deleting the configurations of the 
aplications but don't remmember where the file is and how it is called.
Please, if you have a soution, reply to this message.
Thank you !