Front-page content section

I’m using Newsup v1.9
It looks like there are 4 defined Widget areas which I can add/remove widgets to.
* Sidebar
* Front-page content
* Front-page Sidebar
* Footer

However I don’t seem to be able to find where to modify the displayed widgets.
If I choose Appearance -> Customize -> Widgets it lists:
* Sidebar Widget Area and
* Footer Widget Area
and there is text at the top which says

Your theme has 2 other widget areas, but this particular page doesn’t display them.

You can navigate to other pages on your site while using the Customiser to view and edit the widgets displayed on those pages.

How can I customize the Front-page ? Thanks in advance.