Edit Family Tree Root & Owner

Go to 'Online Family Tree > Configure > Family Tree Root & Owner':

Or click 'Edit Family Tree Root & Owner' on your Family Tree home page:

Enter a name and/or a first name, select the correct individual in the list, then click 'OK':

Links and marks in your Family Tree pages

In the left sidebar of your Family Tree, there is a direct access button to the page of your Family Tree Root:

On the page of individuals in your Family Tree, there are icons (green target) to mark direct ancestors of your Family Tree Root: