Oppo
Set Sound and Vibration for Calendar Reminders auf Oppo
By default, the Calendar app on Oppo phones uses the same notification sound and vibration pattern set for general system alerts. This is controlled per app in the notification settings, not inside the Calendar app itself. Changing it does not affect other apps.
To set a dedicated sound and vibration for reminders, open Calendar and tap Open the Menu. Go to Settings, then General, and select Calendar notifications. There you can choose a ringtone and turn Vibrate on or off independently from your system default.
This setting only changes how a reminder sounds and feels, not when it appears. If reminders are silent even after picking a ringtone, check that notifications for Calendar are still allowed in the system notification settings, and that Focus mode or Do Not Disturb is not muting the app during the reminder time.
If you rely on multiple calendar accounts synced into the same app, this sound and vibration setting applies to all of them together. There is no way to assign a different tone per account within Calendar itself.