3 years ago, I downloaded it and installed CC Illustrator 2017 with a help by my computer woman, who downloaded it in Russian but changed it to English, but 2 weeks ago, my Illustrator changed its language suddenly to Russian (And same is InDesign) though I don't speak Russian. I tried to uninstall it (To reinstall for sure) but with no success. Do you know is there a way to change it back to English? Or shall I reboot my computer (My software is Mac OS Catalina)?
try to uninstall again and change the language BEFORE reinstalling. Open Creative Clouds application, go to File > Settings ("Файл" > "Установки" in russian) > Apps ("Приложения") > find Install section ("Установка") and choose Default Language ("Язык установки по умолчанию") as English