A title field is, by default, hidden. After creating a title field, you can use the Text Menu to make it visible, and specify a larger font.
If you wish to make a title field visible by default, start by creating a document whose title is visible, but without substance, such as the word "Title." Then make this document the Default Genogram. The visible title will now appear on every new genogram you create. Of course, you will need to replace the dummy caption with something more meaningful every time you create a new genogram!