Reset to standard tuning
Make sure you have at least "Version 3.0.3" of the app!
To reset the tuning of any string instrument to the default tuning, make sure the instrument is visible, and a string instrument is selected.
👉 Tap on the instrument title:
👉 Tap on the tuning you have selected (i.e: "Drop D", "Open A"...)
👉 In the list which opened above, scroll all the way to the left horizontally and select "Standard".