If you can't remove a language then this means that you have installed this locale. You can install the en-US version since you have this versions as the preferred language and if necessary install language packs for additional languages. You can find the full installer of the current Firefox release (120.0.1) in all languages and all operating systems here: *https://www.mozilla.org/en-US/firefox/all/#product-desktop-release *https://www.mozilla.org/en-US/firefox/120.0.1/releasenotes/ The first language setting in Settings is about the language for the user interface. The second language setting in Settings is about the preferred languages for webpages. *Settings -> General -> Language and Appearance -> Language *https://support.mozilla.org/en-US/kb/use-firefox-another-language *https://support.mozilla.org/en-US/kb/choose-display-languages-multilingual-web-pages