Hi, can someone tell me how i can change the language from german to english? Though downloaded it in german, wonder if i can change it afterwards without downloading whole game new.

I presume that you're using offline installer? If you don't want to re-download the whole game, you need to use GOG Galaxy. After you change the language in GOG Galaxy game settings, the client will automatically download the necessary files. I don't think there's an option to change the language by editing game files, but maybe someone else will know whether it's possible.

Where can i find the gog galaxy nwn2 game settings? I don´t find it....

I did found it. But when i click english and click ok it doesn´t accept it. It switches to german again....

Well, it should work. Can't check it now, because I don't have the game installed. I'm afraid that you'll need to install it from scratch unfortunately.