Collapsible button goes and hides behind header.

4. Collapsible button goes and hides behind header. I want that be visible & placed below the header "when selected" . please find attached.

I'm sorry, but I'm afraid that this is not possible. This is because of the fixed header of your website. Your other web contents are even doing the same thing. It scrolls up beneath the header/navigation. The Wix builder adds to that. Do you have a way to edit the HTML of a specific fix? Maybe you can play around with it not to have a fixed navigation.