Overriding field label
Actual code should be:

I have used hook_form_FORM_ID_alter() instead of hook_form_alter().

function test_form_user_profile_form_alter(&amp;$form, &amp;$form_state) {
  // Used dpm() to check for picture array.
  $form['picture']['#title'] = t('Profile Picture');
}


Result:


Note: The capitalization of all the character must be coming from theming layer.

Use dpm() for development:
The structure has changed and the account array no longer holds picture array.