If you want to assign multiple contacts that are belong to the same contact group with the same ringtone, you don’t really have to do it one-by-one.
In such a scenario, the quickest way is to change the ringtone of the contact group. If you don’t know how to do this, here’s the guide.
By doing so, all the contacts in this particular group will have their ringtones changed automatically to the one you’ve assigned to the contact group.
It’s that simple !
Note: The steps here were written for MIUI V5, based on Android 4.2.2 on a Redmi (HM1W). If you’re having a different model of Redmi or other version of MIUI/Android, there’s a possibility that the steps and screenshots will be different.