The sort option is accessible vie the arrows on the top-left corner or your screen, when the Setlist view is well-activated. 

There are two sorting options for Setlists: Alphabetical and Custom Sort. 

The custom sorting allows you to sort your setlists as you wish by clicking on "Edit" in the upper right corner and then selecting the 3 horizontal bars on the right of the screen in front of the song name.

To move, tap lightly with your finger to select the line.