Oppo
Custom Ringtone for a Contact auf Oppo
ColorOS stores ringtone settings per contact, not just as one global default. That means you can override the standard tone for a single person without touching the system-wide ringtone in Settings.
This is useful when you rely on sound to tell calls apart, for example to separate work contacts from family, or to instantly recognize an important caller. It also explains why some contacts still ring with the default tone after you changed the general ringtone: a per-contact setting always takes priority over the global one.
How to set it
Tap on Contacts ➔ Choose a Contact ➔ Open the Menu ➔ Tap on Set ringtone ➔ Select from files or choose a ringtone from the list.
Picking Select from files lets you use any audio file stored on the device instead of the preloaded tones. This is the only way to assign a truly custom sound rather than one of the system defaults.
If the contact still rings with the old tone, check that you saved the change and that the contact does not have a duplicate entry synced from a different account, since each duplicate can carry its own ringtone setting.
Per-contact ringtones apply to standard phone calls. Focus mode and Do Not Disturb rules decide separately whether that call is allowed to ring at all, so both settings can work together without conflict.