Syncing is performed by Apple's secure and reliable iCloudKit. Newly entered data is synced in the background when it is safe to do so.
When editing your song catalog it is recommended to do so only on one device at a time. Either close Song One on all other devices or put the other devices in sleep mode.
The changes to a song are synced within 5 to 40 seconds when you:
The changes to a set are synced within 10 to 40 seconds.
The changes to the theme settings are synced within 5 to 15 seconds. Themes may be customized on multiple devices at the same time. The screen on each device will automatically refresh. (Note: Background images are added to the specific song and are synced with the lyrics.)
If you are experiencing a syncing problem try the following options: