Timezone changing is an most confusing task in opencart, as we all know that opencart is written in php, so we try the in built php function to change the timezone. And put that function with specific timezone as a parameter in it and place it in either /config.php or /index.php. But in the world of opencart, things are little bit different. Even though you have edited the config.php and index.php with default timezone function, then also it is not working.
So lets learn the correct way to modify or change the timezone issue in opencart.
Step 1 : Open “system/config/default.php” file
After that save the file and you are done. Timezone will be get affected immediately.