i solved this with some lines of code in functions.php
add_filter( ‘pre_option_upload_url_path’, ‘wpse_77960_upload_url’ );
function wpse_77960_upload_url()
{
return ”;
}
found on: https://www.perun.net/2015/03/09/wordpress-upload-ordner-selber-bestimmen/
thx to Vladimir !
