How to customize the page layout

Hello,

I have a page where there is a space between the header and the breadcrumbs placeholder like this :I need to bring the section which contains this select customer button right below the black header leaving no space.

Can anyone please guide me quickly to solve this ?

Especially the link https://www.outsystems.com/forums/discussion/63648/how-to-customize-the-page-layout/  shared by Miguel Verdasca is relevant.