@pray4afghans the fix is out in Prayer Campaigns v4.20.0.
Here's the release: https://github.com/DiscipleTools/disciple-tools-prayer-campaigns/releases/tag/4.20.0
New sign ups on your 60 minute campaign should now be saved as 60 minutes. Sign ups made before the update stay at 15 minutes.
If you host the plugin yourself, please update and give it a try. Let us know if it fixes it, or if you still see the issue.