If you use Sitecore 8.0 and add a component through the Experience Editor, you will need to add components to each language variant of the subject, i.e. once for English and once for German. This is due to the fact that the components are stored in the field Final Layoutwhen added through the Experience Editor, and the field is language-specific.
The only thing you have is to add components to Shared Layoutmanually by choosing Presentation> Details on the tabs.
, Sitecore 8.1, Edit all versions :

: Sitecore 8.1 update-1, "-" "":
