@crg Extra content areas are in pre-set positions in the page, defined by the chosen theme (all themes will have a different approach to the extra content positions.
Now when you use an extra content area in stacks edit mode, what ever you place into that extra content stack will be presented in the location the theme defined for the extra content area.
So for example, lets say a theme decided that extra content 1 content, should be presented in a banner area directly below the main navigation bar. You can’t change that. If you place an extra content stack in edit mode and define it as extra content 1, then regardless of where in the edit mode screen you place that stack, it’s contents will always appear directly below the main navigation, because thats where the theme says to put extra content 1’s contents.