Samsung
Turn Pop-up Notifications On or Off for an App auf Samsung
Pop-up notifications on a Samsung phone appear as a floating banner over whatever you are doing, then fade out after a few seconds. Some apps switch this on by default, which gets distracting if you get frequent messages or alerts you do not need to see right away.
The setting sits inside each app's own notification categories, not in one global toggle. That means messaging apps, games, and system apps can each behave differently, and you have to adjust them one at a time.
To change it, go to Settings ➔ Apps ➔ [choose the app] ➔ Notifications ➔ [choose a category] ➔ turn Show as pop-up on or off.
If an app splits notifications into several categories, like chats versus calls, repeat this for each one you want to change. Turning pop-ups off does not mute the app: it still shows a normal entry in the status bar and notification panel, just without the on-screen banner.
If your goal is to stop the app from notifying you at all, that is a separate switch higher up on the same Notifications screen, not the pop-up toggle.