so when i look up videos on youtube about how to create a melody there is something that always confuses me. i understand that to make a melody that you stay in a scale and and u can use chords from the scale to create a melody. But in the videos say they pick c major as there scale for the melody they will go down an octave and put notes in like c d e c or something like that and then they will go back up to the octave they want to you and start putting in notes and chords. so what and why did they do that in the lower octave?