Use your computer to drag and drop ringtones to the ringtone folder on your phone. It should appear when adjusting your ringtones. Other methods aren't working yet.
As Colin says, can this be done by PC or just not implemented yet?
Go to settings, notifications, and then chose messaging. There you have a option to change a tone.
Ringtone maker app works again, so no more need for PC to make custom ringtone.
I'm only waiting next build where will be possible to change ringtone and sms tone for different contacts
This^^^You already can in this build, just go to edit contact!!
Looks like you cannot do this in build 10581. If you try the People app wants to send you to the Store. It worked in previous builds so I guess it is a bug which will be fixed. There was an update for the People app yesterday but this situation has not changed.I am using windows 10 in 535 mobile. Even I am not able to assign different ringtones for different contacts..Could someone please help me.