Premiere Pro was the main software used to edit the trailer. It allowed cuts, transitions, titles, and effects to be added to make the trailer look professional. Features like adjusting the editing pace and smooth transitions between cuts enhanced the quality. Using Premiere Pro rather than simpler software like iMovie improved the chance of creating a high quality final product. The document provides screenshots of Premiere Pro's interface and describes how various tools were used to edit footage, audio, add titles, and assemble the edited clips into a sequence.