You want to set the deafult character encoding in the gnome terminal.
Here is a relaed issue:
Here's more direct...
Apparently unrelated issues can hold clues... like:
Seems you can change encoding with the default locale - see man locale for details.
However, in general, it seems gnome dosn't want users setting up broken processes by changing the default encoding.
However: you question says "wrong charset". Are you sure it is the encoding you want to change? Perhaps you want to change the font (edit profile)? Though I admit that anything other than UTF-8 as default is odd ...