To modify this screen on my site I found what I needed under directory: components / com_comprofiler / comprofiler.html.php
Around line 1060 you should find the function pendingApprovalUsers. Just go through this function and you will find the FORM headers, and the next section is the form data. It looks like most of the common fields are brought in as part of the data call. If you need other fields you may need to modify the comprofiler.php file. Again, find the function pendingApprovalUsers in here to make the changes you need.
I recommend ALWAYS making backups of the original files before making changes. Nothing worse than crashing you site and not having a simple file switch to get it back up and running.
Note that I am not an expert, just someone who likes to tinker a bit.
Joomla version 3.5.1
Joomlapolis version 2.0.14