The Assigned Style

Assigned style means that the element (item or group) that uses this style will share the same appearance will all other similar elements that are assigned to the same style.

Therefore, by using styles you can quickly edit the appearance of your menu from a central location: the Style Editor Tab.

Note that you may use the "Customization" feature on specific items or groups to customize particular properties of their assigned style. In this case, any changes you make on their assigned style for these properties will not take effect on the respective customized properties of the items or groups.