GrapheneUser
Push the volume down button then change this to silent then vibrate or sound: (see pic below)
https://imgur.com/a/K2kjW4l
Also tap the 3 dots at the bottom of the volume bar that pops up. Set your ringer and notification sound to the appropriate level.
Repeat this for every troublesome app:
Hold your finger down on the app's icon for 2 seconds that isn't vibrating or making a speaker noise > app info > notifications > expand the options.
You should see a bell icon by each category. No bell icon means silent. (No vibration/chime)
There is also, as you might have noticed, individual conversation settings to check here as well if you made any customizations to a person. For example, you can set 1 person, Jelena, to be silent, priority, no vibration, etc.
Lastly, reboot the device.