Nope, sorry Carl. I'm having the same crazy difficulty trying to find where and how to change or even add ringtones. There is no "Sound & Notification" category like on most phones. There is a "Notification Drawer" category but no sound setting. I've looked in all the setting categories and found nothing. No owner's manual either which I'm looking up. Will let you know when I know.
Go to Settings > Sound & Notification > Phone ringtone. Please let me know if that's what you're looking for.