Cinobo is set to English but I want it to be set to Greek or Polish (or vice versa)

On a browser: Find the language indicator in the top right and select your preferred language or if you are logged in, click on the three lines symbol in the top right and select your preferred language there with the language indicator. On mobile, you'll find it inside the menu, still in the top right. This changes only the interface language, not subtitle options.

On apps: The Cinobo app on smart TVs, Apple TV, smartphones, and tablets automatically follows your device's language setting. To change the app's language, adjust your device's system language settings.