Huawei
Set a Custom Notification Sound Per App auf Huawei
On Huawei phones running EMUI, the notification sound you set under general sound settings only applies to system alerts, not to individual apps. Each app manages its own notification sound inside its dedicated settings page, which is why WhatsApp and Messenger can end up sharing the same default tone even after you changed the ringtone elsewhere.
To assign a custom sound to one app, go to Open the Settings ➔ Tap on Apps ➔ Tap on Apps ➔ Choose an app ➔ Tap on Notifications ➔ Tap on Miscellaneous ➔ Tap on Sound ➔ Choose a notification sound.
Repeat these steps for every app where you want a distinct sound. This is useful when you rely on several messaging apps at once and want to hear which one is buzzing without picking up the phone.
If the Sound option does not appear, check whether the app has its own in-app notification settings instead of relying on the system menu. Some apps route sound choices through their own preferences screen rather than through EMUI.
Battery optimization can also interfere: if a background app is restricted, its notifications may be delayed or muted even after you set a custom sound. In that case, check the app's battery permissions separately from the sound setting.