How to change the Header Picture in other Menues

when I create a new side, there is to the picture from the design, wich I cannot change.

when I named a side and want to make the title unvisible it not worked too

Hi there,

the site you imported is using a Header Element which is controlling the Header background image:

https://docs.generatepress.com/article/header-element-overview/

You will find them in Appearance > Elements.