Most of those who are on shared hosts doesn't happen or find a way to change them. And they are hardly visible if you have dark themes. Here's an easy way to change them which I used when I was a shared hosting user long ago. Moreover I saw a similar thread today so wrote a quick tutorial.
Open showthread.php (You can find it in your root directory, i.e. where index.php, etc, files are located).
After:
Add after it:
Edit the above colors with your choice and save the file. Now you should have the custom highlighting colors.
Open showthread.php (You can find it in your root directory, i.e. where index.php, etc, files are located).
After:
Add after it:
Edit the above colors with your choice and save the file. Now you should have the custom highlighting colors.