Select the element with mouse, then you can set the property of the text in this element. For example, font, size, style, frame, color, background and position in the element.
After above setting, the element changes into:
Drag the element to certain position in the Flying subtitle design window, the position will directly show in the video; you can also set the motion property of the element (described later). Click to preview the effect of the Flying subtitle. Finally click save, then you get a Flying subtitle file that consists of text element.