When you enable chord diagrams for your charts, you may notice that a default chord diagram is selected out of a number of variations. You can change the default variation that is picked using the Chord Diagram Library.
Tap on the gear icon in the Menubar to open the Utilities Menu and then choose Editors and then Chord Diagram Library. Locate the chord on the left and the diagram variations will display on the right. The order of these chord diagrams is used to determine the default chord to display. So naturally, the first chord diagram is the default. You can then select a chord and tap on the icon in the upper corner to open the Actions Menu. You can then choose the Set Default. This will move that chord to the start of the list.