Welcome message adjusted to user's browser language

Hi everyone!

We would like the welcome message to be shown in the user’s browser language. We have tested diverse settings and were only able to set English as default. Before it worked, we had an English version if the browser used English as default language and German when German was used. Now if a user has French or Spanish as a browser language they are directed to an very old welcome message we cannot find in the admin settings.

Would anyone have an idea how to solve this?

Many thanks for your help!

You can find that or any other message by searching for a string in Admin → Customize → Text: