This adjustment is made at the instrument level in the editor and is not global to GigaStudio. Go into your instrument editor, load the instrument you wish to change the pitch bend range of, and at the left, right click on the instrument under the Instrument Bank 0. Go to Properties, and set the Pitch Bend (semitones) to the desired value. You will need to re-save the instrument. Your pitch bend range is now set for this instrument.