Ringtone volume on Iphone 6s?

I have an Iphone 6s and up until recently I just used the default ringtones and such. Although I recently downloaded a new ringtone and set it to be the ringtone for just one of my contacts. However, there's a problem with this.

The ringtone is extremely loud, and I do not want it to be loud I want it to be the same volume as the other ringtones. Now I know I can just turn the phone's volume down, but this makes all the default ringtones and text alerts too quiet to hear.

So my question is, how do I turn down the volume on just that one ringtone, while leaving the rest of the ringtones and alerts at the normal volume?

Download it from your phone - drag it onto your computer. Use AUDACITY to lower the volume of this, then save it. Then put it back on your phone. IF this is too complicated for you - there are geeks everywhere who do this for fun - and a bag of Cheetos.