i can choose between preferred installer languages but the files are the same when i wanna save them so i wanted to ask if i need to download everything new and swith the installer option or can i change the language in game and just need to download the game 1 time?

gog.com support SUCKS! they always dont reply, wtf is up?

This is not a support forum, but a community discussion, just in case you though otherwise.

After a quick googlesession Iv'e found that if you wish to change the audio language of the game you don't have to re-install it, it'll suffice to download language packs from the official page:

http://en.thewitcher.com/ee_manual/

Go to the bottom of the page and choose the preferred audio.

Also, for quicker responses in the subject of TW2 I'd advise trying the official TW2 forum over at:

http://en.thewitcher.com/

Hope this helps!