My guy what that statement from YouTube is saying is that not all of your subs get notified when you upload. That doesn't mean not all of your subs will see your video in their feed, they just won't get a message from YouTube the exact moment you upload. Your video still gets put into their sub boxes. Of course ringing the bell means you always get a notification when that person uploads, that's the whole point of the bell. If you click it it means you want to know exactly when someone uploads