Today, I had two notifications in the morning. One for a text message and one for a Telegram message. The notification's icon at the top of the screen was highlighted as normal. Then while trying to make a call, my phone crashed and I needed to restart it. When it came back up the notifications for the two messages had gone and the notification icon (at the top of the screen) was normal.
What settings do I need to change to stop this from happening in the future? As if the phone goes down, battery goes, crashes or anything like that. I do not want a situation where I do not know about messages, emails, calls and such like as the notification has been cleared down and not by me actioning them.