Figma sites : breakpoint updates

I everyone, I need help with figma sites.

When I use Figma Site and I try to edit text in a section, for example in the header, it doesn’t automatically update in the other breakpoints, same things for pictures, they don’t update on other breakpoints. However, if I delete a section, it does get removed across all breakpoints, and the same goes for deleting a text block, it disappears everywhere.

Can someone explain me what am I doing wrong please ?

Thanks, 
Arthur