Hello anczor,
Thank you so much for using our theme Mercantile. All the options of the theme are under Appearance > Customize. Please check all the available options there. We recommend you to use the theme documentation for more help regarding the theme. Please follow the every steps of doc for theme use.
All the theme have options to change the section through theme options, no need to use FTP for such things.
Regards
Acme Supports