If you want to change timezone for a single account on a cPanel server you can follow following simple steps for this.

1) Login to the server as root.

2) Navigate to the home directory of the account and create a .htaccess file. If it already exists you can add the following line to the top of the file.

3) Insert the following line in it

SetEnv TZ “TimeZone”

or

php_value date.timezone “TimeZone”
Replace the TimeZone with appropriate time zone as per your convenience. For Eg:: Asia/Calcutta

Refer PHP: List of Supported Timezones - Manual for the list of available timezones.

You are done.