There are three ways to edit the songs of your songbook:
Edit your songs directly on your device. No need to be online. There is a video that shows you how: https://youtu.be/QGxaxAS6Dwk
Edit the songs comfortably in the browser of your computer. There is another video that shows you how: https://youtu.be/19JVc76ExkY
Synchronize your songs with your cloud. Edit them in your cloud and start the synchronization again