OppoA7x sets the volume with a volume key which is adjusted by default, and there are two volume keys in it. What do they stand for by default? By default, they stand for media and ringtones.

The buttons on the side of the phone frame can adjust the volume. The upper button is to increase the volume, and the lower button is to decrease the volume. The volume button is adjusted to the media volume by default. You can change the ringtone volume in the settings.

Setting path: "Settings > Sound and Vibration >: Default adjustment of volume key" is changed to ringtone volume.

This answer applies to all OPPO models.