Hey, You can switch languages at any time to display Firefox menus, notifications and messages in a different language. 1. Click the menu button and select Settings. 2. In the Language section of the General panel, choose a language, in your case "US-English" in the drop-down menu. 3. Restart Firefox. Refer to below attached link for further details. https://support.mozilla.org/en-US/kb/use-firefox-another-language#w_switch-firefox-to-another-language

Is this about the language of the Firefox user interface or about languages used on webpages ?

If the Firefox user interface (toolbars) is in the wrong language or if you want to change the current language then download Firefox in the language of your choice.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

The language setting in Settings is about the language for the user interface and the preferred language for webpages.

• Settings -> General -> Language and Appearance
• https://support.mozilla.org/en-US/kb/choose-display-languages-multilingual-web-pages