Oppo
Custom Notification Sounds per App auf Oppo
The main sound settings on Coloros only control the phone-wide default notification tone. That switch does not reach into individual apps, because each app manages its own notification channels once it has sent at least one notification.
To change the tone for a single app, go through app management instead of the sound menu: Tap on Settings ➔ Tap on App management ➔ Tap on App list ➔ Choose an App ➔ Tap on Manage notifications ➔ Choose a Category ➔ Tap on Ringtone ➔ Choose a Ringtone/Sound.
Most apps split their notifications into categories, such as messages, calls, or system alerts. Each category can carry its own sound, so a messaging app can ring differently for a direct message than for a group update.
If an app has not sent any notification yet, it may not show up with categories in that list. In that case, wait for the first notification or trigger one manually, then repeat the steps above.
This method changes only the sound. It does not affect vibration patterns or whether notifications appear on the lock screen, which are handled through separate switches in the same category screen.