Why can�t I put in quotes?

[hugo vanwoerkom]

In mozilla (since 0.9.6) I am unable to use the quote symbol, it
always comes out a question mark. In the subject of this post I hit
the single quote and somebody made that � When I hit the key it
was a question mark. Yet in the same X console this works with 4.79.
Where do I look to fix this?