I can't find my ringtones as an option for reminder notification sounds

First - I'm a new iphone user, so let's just assume I don't know where to find things :) I just created a ringtone to use as a notification sound for a reminder. I went to Settings - Sounds & Haptics - Reminder Alerts and all that is there are the default notification sounds that came with the phone. No ringtones. I've seen others mention that if you scroll down past the tones, you'll find the ringtones, but I don't have that - all I have are the tones. If I click on ringtone instead of reminder alerts, the ringtones I have created show up there - but not under the reminder alerts. Can someone help me get my ringtones to show up as options for reminder alerts? Thanks!