You have a boilerplate and wondering where the content is coming from? Click at the header/footer to find out.
When the header/footer is locked, uncheck the checkbox Lock this block
Is a pop up like this visible? That means that your header/footer comes from Skins and is edible there.
When the header is edible directly in the email draft/boilerplate, it has no connection to Skins.
It can be possible that the logo or text elements are coming from Skins, but not the header/footer framework. But it is easy to see - when you see a handlebar starting with {{config.data. instead of a text, it means that the content is from Skins.
Has the header/footer no connection to Skins, you need to create new email drafts after you changed something in the boilerplate.
It can be possible that not all content from your custom header/footer is changeable in Logos Content or Style - Icons in Skins. Then, it might be the case that some content e.g buttons or when you use other icons than Social Media Icons and Other Icons is directly in the footer code that can be find in Layout - View code. It is possible to change the code there, but you are always welcome to contact your account manager or our support team and ask for help.