Hi @iamelisabethparker,
There are multiple points on your question which we need to separately address and I strongly suggest that you open up a separate thread for each one.
1) The white screenshots that there is a PHP fatal error but your server and WordPress installation are configured in a way that does not show the errors. You will need to contact your hosting service provider and ask them to enable the PHP Error Display and also you need to enable the WordPress Debug mode. Then you will see the actual error causing the issue. You can also contact your hosting service provider and ask them to check the error log and give you an answer.
I suggest that you get help from the hosting service provider also for the WordPress debug mode.
2) Pro WILL NOT give you additional options regarding the Icon layout. It will have the same layout as X and the sidebar will be separate and you Can Not change that behavior as the Icon stack is designed that way.
3) If you only want to add a code to the header of the website and you are not interested in the header builder which is the main cause of the Pro purchase, I suggest that you do not convert to Pro.
4) If you want to add a Javascript or HTML code to the HEAD tag of the generated HTML you need to install a Child Theme and add the code below to functions.php file:
add_action('wp_head', 'head_information', 9999);
function head_information () { ?>
<!-- Your HTML Code Here -->
<?php }
Add your code instead of the <!-- Your HTML Code Here -->
part.
Thank you.