How do I stop international language from appearing in some Safari windows?

Question

After selecting Polytonic Greek as one of the languages for use in composing text (MS Word), I found that Greek appeared as the default language in certain Safari windows, typically those (like a university email account I use) that are configurable for people of many nationalities. It's maybe worth noting that when Greek appeared in my Mac's language menu, it appeared above US English, unlike the other languages I use.
None of the following have fixed the problem:
--Deselecting Greek and restarting/shutting down (multiple times)
--Clearing the cache and history in Safari (multiple times)
--Running Disk Warrior and Drive Genius, my standard system maintenance software
How can I get rid of this now unwelcome language?

Answer 1

I found Greek at the top of the language list, above English. I think that made it the default language in certain circumstances.
Yes, having Greek at the top of that list does several things: Any app which has a Greek version will open with its menus and dialogues in that language. If you have installed a Greek spell checker, that will become the default in all Apple apps. And Safari will ask for the Greek version of any web site that offers that as an option. On the list, Greek appears as Ελληνικά.