Xiaomi
Set a Custom Ringtone for Calls auf Xiaomi
Xiaomi phones ship with a preset list of ringtones for incoming calls, but MIUI also lets you assign any audio file already stored on the device, including a full song, without copying it into a special folder first.
To change the tone, open Settings ➔ Sound & vibration ➔ Ringtone. On dual SIM devices, pick the SIM card you want to change first, since each SIM keeps its own ringtone setting.
Tap All ringtones, then Choose local ringtone. This opens the File Manager, where you can browse to any audio file saved on your phone, whether it sits in Downloads, Music, or another folder.
Select the file and tap OK to apply it right away as your new ringtone. MIUI keeps a reference to that file location, so moving or deleting the file later removes the custom ringtone as well.
If the tone does not change after saving, double-check that you picked the correct SIM card and that the audio file plays normally outside the ringtone picker.