Unfortunately, that’s not how the “extra capability” setting works. It doesn’t replace the existing required permissions; it’s an additional requirement. If you set it to “editor”, the user will need to have both the required capability and the “Editor” role to access the menu. So if the user didn’t already have access to the menu, changing “extra capability” won’t give them that access. Generally, the free version of this plugin can’t be used to give roles access to menus that they normally can’t see.
Instead, try using a role editing plugin (e.g. something like User Role Editor or Members) to enable the “edit_theme_options” capability for the “Editor” role. That should let the role access most theme settings.
