The bar at the top of every page crops your cover and your picture to fit its height. Where that crop lands depends on your images, not on a default — so pick it. Changes apply to the bar above as you move them, and are kept on this device.
Your uploaded picture always wins. These are for when there is none — or when the one you have cannot be reached.
Every container you follow sends its releases and alerts to your notification panel. Turning one off stops its notifications; it does not hide the apps, which stay open to you either way.
Where the apps read something from outside Feerebu. Most of these are open public data and need nothing from you. Where a service does take a key, it is your account with them — supply it and the apps use it instead of the shared anonymous limit.
A token lets a script read your own data — your usage log, your analytics, your saved files and your export — and nothing else. It cannot change a setting, touch billing, or issue another token. Shown once when you create it, stored only as a hash, and revocable here at any time.