Admin username highlighted in a different colour

depending on your theme, you might be able to add an author role specific css class to the post div or the author name output.

name and download link of your theme?
link to your site to illustrate your issue?

Link to the site: https://www.Nave360.com
Theme: (its paid) https://themeforest.net/item/leetpress-a-gaming-wordpress-theme/232177

difficult –
a: because with a commercial theme, there is obviously no free access to the template files which makes any support extremely tedious;
b: the theme has no distinguished span or class for the author link.

have you checked with the theme vendor if they have a support forum?

you could paste the code of single.php of your theme into a https://pastebin.com/ and post the link to it here, so someone can have a look if there is an easy enough possibility to add an extra css class to the author link.

https://pastebin.com/SEGPMapT

example:

try and change this line:

<p class="post-meta">Published on <?php the_time( get_option('date_format') ); ?>, by <?php the_author_posts_link(); ?> - Posted in <?php the_category(', ') ?> <span class="meta-comment"><a href="#respond"><?php comments_number('0', '1', '%' );?></a></span></p>

to:

<p class="post-meta">Published on <?php the_time( get_option('date_format') ); ?>, by <span class="author-level-<?php echo get_the_author_meta('user_level',$post->post_author); ?>"><?php the_author_posts_link(); ?></span> - Posted in <?php the_category(', ') ?> <span class="meta-comment"><a href="#respond"><?php comments_number('0', '1', '%' );?></a></span></p>

https://codex.www.ads-software.com/Function_Reference/the_author_meta

add something like this to style.css:
span.author-level-10 a:link { color: #123edf; }

https://www.w3schools.com/css/css_link.asp

is author level 10 administrator?

is author level 10 administrator?

i think it is.

https://codex.www.ads-software.com/Roles_and_Capabilities#User_Level_to_Role_Conversion

ok i replaced the code with the one you wrote, and i also added span.author-level-10 a:link { color: #123edf; } below general styles in style.css but replaced the colour to #FF0000 and i can’t see any change =(

Oh wait… it was my browser! it works fine! Thank you so much, you helped a lot =)