Using an Overlay Graphic
The first step to creating a button over video subtitle using an overlay graphic is to import
the overlay graphic into the subtitle.
To import an overlay graphic for a button over video
Select the subtitle clip that you previously created to configure for buttons over video.
Click Choose in the General tab in the Subtitle Inspector.
In the dialog that appears, select the graphics file to use, then click Choose.
The graphic appears in the Viewer tab, using the current settings in the Colors tab.