First, go to your home screen. Find the Phone app and give it a click. Alternatively, you can open the Contacts app, if it is readily available to you on your iPhone's home screen.
Click "contacts" at the bottom of the screen.
Select the contact you want to change the ringtone for.
Click "edit" in the upper right-hand corner of the screen.
Click "ringtone default." It may not say "default" if you have changed the ringtone before. In that case it will say "ringtone" followed by the ringtone name.
This is where you can also choose "text tone default," if you want to change that contact's text tone versus its ringtone. The process is virtually the same.
Select the ringtone you would like to use for that contact.
Of course, if you want to get fancy you can buy a ringtone to use with your contact. Maybe you want it to be that contact's favorite song or favorite TV show theme song. Either way, this process is super simple while adding just a few additional steps.
To learn how to buy a ringtone to use for that specific contact, or many others if you choose, check out my guide on how to buy a ringtone for an iPhone contact.
Once you have selected your contact, click "done."
Make sure the correct ringtone is selected. You'll be able to see on that contact's contact page after clicking "done" in step eight.
And... you're done! you've successfully changed the ringtone for your contact of choice and can now move on to the other contacts you want to edit!