Changing default language

Hello, I have a question about the default language of gallery2. I have a website running with multilanguage (english/italian). The default language is english and so, when I add a new photo I first insert informations in english and then in italian in the multilanguage tab.
What happens if I want to change now the default language of the site to italian ?
Do I need to change the default caption of the images from english to italian or are the language informations automatically changed ?
Thanks for help