The Frame Properties toolpane in the Topic Editor contains settings that allow you to change the appearance of the bubble and bubble text, as well as describe the action performed in the frame.
The Frame Properties toolpane has two sections, separated by a divider bar. The section above the divider bar contains the options for the bubble and bubble text, and the section below the divider bar contains the settings for the action. You can drag the divider bar up or down as needed, for example, to see more of the bubble text in the upper section.