In cPanel File Manager you can set permissions for files. This means you can set who can read, write and execute a particular file. Sometimes you will need to change file permissions for script installations. 

To change file permission in cPanel:

1. Connect to your cPanel account
2. Go to File Manager (FILES section)
3. Navigate to the file  (you can also select multiple files)
4. Click the Permissions link from the top menu
5. Select the desired file permission in the Change Permission window
6. Click the Change Permissions button.

Some common values for file permissions are:

777 – anyone can read, write and execute the file
700 – owner can read, write and execute the file
666 – anyone can read and write the file
644 – anyone can read the file, only owner can write it
600 – only the owner can read and write the file
400 – no one can write the file; only owner can read the file

If you have SSH access to your account, you can change the file permissions by using the command:  

root@web [/]# chmod 400 filename.php