Customize > Footer options section provides a set of options for customizing the footer area.

Here you can find 4 sections with different options. Let's review each of them in detail.

Widget section allows configuring the footer menu and logotype sections.
Widget block width allows you to set up the width for the footer menu columns. Each column is a widget, which you can manage under Appearance > Widgets.

Footer was built with Bootstrap grid, so, you need to select the width of the menu column multiple 12 column grid. The selected width will be applied for all the columns (widgets).
If you enabled showing text block, you'll be able to adjust the logo section in footer.
Text block width allows you to set up the width of this section. It's also built with Bootstrap grid, so, you need to select the width of this column multiple 12 column grid.

The text of this block can be edited under Text block content:

Under text block alignment you can set up the position of the text block.

If you enabled showing a logotype block, you'll be able to adjust the logo in the footer.

You can open extended logotype options by clicking to 'Define website logotype'. Here you can set up the logotype image, enabled logo in the retina, change the logotype text and description.
Here you can set up links to other social network pages according to your needs.

Footer Design section provides options for adjusting different options such as text color, widget titles/links color background color/image etc.
Let's review every option in details.
If you switch to 'Yes', all the footer content will be expanded in full width.
Text color sets up the color for the text block below the logo section.
Widget titles color sets up a color of the title for every footer column and social sharing icons.
Widget links color sets up a color for the footer links.
Background color sets up a general background color for the footer area.
Background image sets up a general background image for the footer area. The background image takes priority under the background color.
If you switch to the 'Expand background' button, the background image will be expanded in full width.
General footer menu sections can be edited in the backend under Appearance > Widgets > Footer Widget Area.

However, if you click to one of the pencil icons, you will be redirected to Customize > Menus > Main links (footer) section and will be able to customize the footer menu via the frontend.
Then the menu section will be opened and you can edit the menu name, its links or delete it. Besides, you can duplicate the footer menu in one of the offered places by putting a tick for the necessary menu location.
Here you can control the appearance of the 'Scroll to Top' button by changing background/icon color for it.

Here you can configure copyright information, which appears at the bottom of the footer.