If you want to change the server time zone, there are several ways to do it. One and most common is to do it in your admin panel of your app, or configuration file.
In case you want to use another way, you can do in on server side in your hosting account
Simply go to your Control Panel, click on File Manager and navigate to your .htaccess file. Usually it is located in your root folder of your app, or public_html.
Open the file and insert the following code:
php_value date.timezone 'Region/Zone'
Where the region is the continent and the zone - city
Here is an example:
php_value date.timezone 'Europe/Sofia'
Note: In case it doesn't work, please put the code higher in your htaccess file.