Possibly like
https://xoops.org/modules/newbb/viewtopic.php?topic_id=68768&forum=7&post_id=312849#forumpost312849

I have been asked to put email
username and passwords fields after the other fields in the User Profile Module
I have looked in the module in register and templates, and cant see how to alter them to get this effect? looked in profile_register.html and others ...

Found it in /modules/profile/include/forms.php
added number 14 where was 0, ( a kludge).

$elements[14][] = array('element' => new XoopsFormText(_US_NICKNAME, "uname", 35, $xoopsConfigUser['maxuname'], $user->getVar('uname', 'e')), 'required' => true);
$weights[0][] = 0;
still looking on how to add coments to field. (dec?)

my problem has been fixed by upgrading to 2.3.3