For the Twitch issue, it's likely that Twitch stored a secret in your Keychain that persists. If you have a Mac, you can enable iCloud Keychain on your devices

For the Twitch issue, it's likely that Twitch stored a secret in your Keychain that persists. If you have a Mac, you can enable iCloud Keychain on your devices to sync and explore the contents. Search for Twitch and delete the entry(ies).