You can change the permission or chmod file in a few steps:
cPanel - File Manager - location of that file (example /public_html/config.php)
Right click on the config.php file then "change permissions", a new window will open where you need to enter the permission number (say 755). Of course, you can also tick if you know exactly what you need.
You have three modes and three types of permission. Depending on who you want to access the file, you tick it. We strongly recommend that you follow the instructions and enter the number in the instructions that led you to change the permission or chmod on that file.
If you make a mistake and deny access to someone, the site will not work. Of course, it's nothing terrible because you can return to the previous state with the same procedure afterwards. But it is very dangerous if you allow everyone to see your config.php file and thus jeopardize the security of your site.
