Language
One language for the portal
«App and panel language» is set by an administrator and applies to the whole portal: the app, the operator panel and the start-page panel. It is not a personal preference.
A portal that has never chosen a language stays Czech.
This website
The public pages have their own CS | EN switch. That switch saves a cookie in your browser. It does not change the language inside Bitrix24.
The page you are on
The manual follows the language of the address (/en/ or /cs/). The in-app language and this website are independent.