Preferred mail format select does not set current value
It has been fixed in the updated version https://issues.civicrm.org/jira/browse/CRM-19135. 

So it's recommended if you could upgrade CiviCRM to 4.7.11 or apply this patch to your site and check if it works for you https://github.com/civicrm/civicrm-core/pull/8777