I bought my Nokia 8 phone in November and have been loved it. Had to switch it off the other day and when I restarted found that the OS had changed to Android Oreo. Several apps no longer work. The OS is an ugly mess. The worst thing is that my phone keeps randomly playing the notification bleep (screen does not light). When I look at the phone's notification screen, nothing is showing. It's driving me mad. I can't tell what app is causing the notification bleep.
How do I revert back to Nougat? And stop the OS from auto updating?