How to create webform according to user rules
you need to try this coding
  

function _form_edit_module_form_alter(&amp;$form, &amp;$form_state, $form_id) {   
 if($form_id =='webform_form_id') {           
  //check login user enter in site
  global $user;
  if ($user-&gt;uid) {
     $form['component_name']['#attributes']['disabled'] = true;
  }               
 }
}


and also you need check  Webform Conditional module