Loading indicator z-index
I'm sorry, but I don't follow you. Please try to explain using some screenshots.
ok @anonimniq, Thank you for clarification.
There are two options I can suggest you.
1. You should add the following js code in your active theme js files (it'll show the loading bar in the top menu section).
jQuery( "body" ).append( jQuery("#wpdiscuz-loading-bar") );
2. You can move the loading bar to the center of your webpage via the following CSS code:
top: 50% !important;
left: 50% !important;
The CSS code should be added in the "Custom CSS Code" textarea, located in the Dashboard > Comments > Settings > Styling admin page.
In any case please don't forget to delete all caches before checking.