Appearance > Menus
A submenu is configured through its parent menu item’s settings. So, if you have a menu item named Places, the submenu of Places can be configured in the Menu Item Settings of the Places item.
To view the Submenu Settings, open the Menu Item Settings by hovering over the menu item and clicking the Uber button. In the Menu Item Settings Panel, click the Submenu tab on the left.
This panel allows you to control the type, position, size, layout, background image, and more of this specific submenu.