Why does FaceTime ring on all my devices? Have tried everything!
It sounds like you have the same AppleID on all the devices. The default is that all devices configured with the same AppleID use the primary email address associated with that Apple ID. 

You have a couple of options:


Use a different AppleID
Use a different email other than the primary one.  There's an excellent article on how to do this workaround 


Basically, you go into the Facetime settings on on each device you don't want to ring and add another (different) email.