Sounds on IPhone XR

I don’t know what’s wrong but my iPhone XR has problems with sounds. For example : you are sitting and scrolling up the news and you received the notification. But sound of notification is really loud(even if I have volume is very low) because you are touching your screen. If you don’t touch you screen, it’s all okay. its really strange and sometimes scary because you receive notifications unexpectedly and at full volume, which in fact you didn’t turn on.