修改Optimizepress的头文件[op_theme_file（'header'）]

I have tried to edit the default header of Optimizepress, I have edited the blog header, but it seems I can't edit the default page header. On header.php its written

<?php op_theme_file('header') ?>

But I don't find the exact location where the header is located to modify.

Thanks

Landing page : optimizePressTheme/pages/landing/1/template.php

Marketing : optimizePressTheme/pages/marketing/1/template.php

Membership: optimizePressTheme/pages/membership/1/template.php

 op_theme_file('header')

Where header page comes from the depend on your page; it's come from base on landing, marketing, and membership page ...