Changing field instance display settings for view_mode Background

In the user.module file in user_build_content(), there is a line that adds fields for a given view_mode:

$account-&gt;content += field_attach_view('user', $account, $view_mode, $langcode);


The documentation for the field_attach_view() function says 


  Each field is displayed according to the display options specified in the
   $instance definition for the given $view_mode.


Digging further, I find that the instance definitions are loaded/cached using FieldInfo-&gt;getBundleInstances(), which loads them from the field_config_instance table in the database in field_read_instances().

Question

I have some custom user fields already being displayed for the 'teaser' view_mode, to the exclusion of others, and I cannot find where this is coming from since no hook appears to do it in the code.

How do I change the display settings of a field for a specific view_mode? Is there a place to do this in the field UI somewhere?

Edit: I found the defaults coming from hook_field_default_field_instances(), which were exported into a module using the Features module. Can anyone tell me where I can change them in the UI in order to re-export the feature?
This took me so long to find. Account Settings -> Manage Display

admin/config/people/accounts/display/teaser