It sounds like you might have the English version of Firefox installed. This might have happened for example if your language settings were not set to Finnish at the time of downloading. Unfortunately, adding or switching languages after installation is technically different and does not always work as well as selecting the language when installing. To fix your problem, I recommend to reinstall the Finnish version of Firefox. To make sure to download and install the Finnish version, please select the Finnish language on this download page: https://www.mozilla.org/fi/firefox/all/#product-desktop-release Please say if this fixed your problem or if you need further help.