In order to change the permissions for a particular file/folder we need to perform below mentioned steps:

1) Login into cPanel of their domain.
2) Click on file manager and go to the file/folder to which we need to assign require permissions.
3) Click on file/folder name.
4) Change permissions option will appear in the right upper corner so click on it.
5) Select the check box upon require permissions.
6) Click on save.