GMail via Mac Safari thinks I'm German

I have used Gmail in other browsers without a problem. After installing it in Safari, it kept underlining my English words as misspellings and offering German words to complete the words I was typing. I went to Preferences where I confirmed that English was my preferred language. My only hypothesis for what happened is that my first contact via Safari Gmail was from a German address, though the communication was in English.

I thought to uninstall and reinstall Safari, but uninstallation is not permitted on a Mac

Any ideas, please?!