In order to edit data:

(1) Click on "Turn on manual mode" button so "Manual mode: TRUE"

(2) Edit numbers in the data frame

(3) Click "Generate!" button in the bottom-left corner

(4) Switch tab to "Visualisation" or "Parameters" to see updated sounding (it may take several seconds)

(5) Return to "Manual mode: FALSE" if you wish to restore downloading new data