Hi,
i cant french, i try in english.
I dont really see which system you mean.
When it is dreamcast:
You can set the language in the BIOS settings.
Start a Dreamcast game and then press START+A+B+X+Y
In the BIOS settings four symbols appear.
The symbol below right
is the one which include the language selection.
How i know you must do this only one times. Try it out and give feedback.