Ok. How are you muting your sounds? Settings > sounds and vibrations? Because that doesn't control all your notification sounds. Settings > apps will get you to each app in which you can configure individual notification tones. Do you want them off at night? Then that's going to be settings > notification > do not disturb. You can set what comes through, who comes through and when they come through with time of day.
Or do you want total silence for a short time? Pull down menu from the home page, click the icon that looks like a speaker with sound waves coming out. 1 click mutes, but leaves vibrate on. Click again, no sounds, no vibrate. Click a 3rd time, sounds come back.
So how are you trying to mute? Not trying to be sarcastic, but some people click the wrong button.
You're right. I called and discovered my notification sounds wasn't established for media storage...it's set now and I selected Silent (which wasn't available due to my failure to set it up). Thanks for your help. I'll try to mark my post as resolved.