Question: how to customize notification sound on samsung a20?
Answer: Notification style. Tap then select the desired option (e.g., Sound and pop-up, Sound, Silent, Silent and minimized).
Sound. Tap to select the desired option (e.g., Default, Silent, etc.).
Vibrate. Tap to turn on or off.
App icon badges. Tap to turn on or off.
Lock screen. ... 
Ignore Do not disturb.