Not working on youtube, gmail?

[mzso]

Hello!

These two websites are the main ones where I would switch between languages, but this addon never does. No matter how many words I write.

[ScienceDiscoverer]

Read the Readme file:

If this extension doesn't work for you for a specific site, you probably have a content preference that overwrites the dictionary for that site. This content preference is automatically added if you manually set the dictionary for an input field on a site. In order to clear it, try manually setting the dictionary to the same language as the site, e.g., English for Reddit.

If that doesn't work, you can manually clear all content preferences by deleting the content-prefs.sqlite in your profile directory. On Windows, this can be found in a subfolder of %AppData%\Mozilla\Firefox\Profiles. Please note that this will also delete other content preferences you might have set for different sites, such as the zoom level and the default download folder.