On mac preferences are always accessible via the application menu (click calibre) in the global menubar. This is the "standrad" location for preferences in mac apps. They are also available via the mac standard shortcut of Cmd+,
@divingduck: The shortcuts are not defined by the ampersands. This is hte relevant translation in german. Someone seems to have translated Ctrl to Strg, causing the problem:
https://translations.launchpad.net/c...earch=Ctrl%2BP