I know that the support for Adobe Reader X it is terminated. However I'm still using it and I cannot upgrade since a software that it used in my company it is only compatible with latest version 10.1.16.
The English version provides the sign function in the toolbar. While in the Italian version the sign button is not available and I cannot add it to toolbar menu.
The sign function is present in the menu under view->show/hide->navigation panel even if it is shadowed and I cannot click it.