If I am not logged in, the settings button is still visible in the sidebar (on the playgroud). Since all the settings are tied to a user account, the button should be hidden.
Totally possible, but that functionality is not there right now. Settings are stored on a user object, which only exists if the user is logged in. So if you are not logged in, changing the keybinding does nothing. I agree that they should be changeable though.
If the user is just trying out the playground, why can't they still eg. set their key bindings to Vim, if that might make them enjoy the product more? And if they don't log in, that setting just won't persist (unless we store it in another way).