Hi,
Try removing autocomplete="off" in the file /modules/mod_easysocial_dropdown_menu/tmpl/default.php
This works for me in Firefox but in Chrome, due to the fact that the form has a display:none, the form seems to be not auto filling. Removing the display:none on the dropdown however, Chrome will then autofills it properly.
I am not sure if this is a Chrome issue. Will have to research more on this.
UPDATE:
Upon further testing, it doesn't work on Chrome due to a technique of popbox that we are using. The form is cloned from an existing form that is embedded on the page, and when the element got cloned, Chrome seems to not populating the form properly. This is because forms are populated only on page load, and any forms created after that won't get populated.
I will have to discuss this with the developer to see how to remedy this.