German special chars "Umlaute" not displayed properly

I use Firefox 3.0.19 on Ubuntu Linux (Hardy Heron).

Why are my german special chars like e.g. ä, ü, ö displayed wrong like this?

Where can I set UTF8 as charset or switch language setting to german?

Hi, I have found a workaroung. You can write text in another app and then copy&paste it into prezi……