How do I update the time?

The time stamps on activity in my network are an hour out, this is despite the fact that in Plesk the server system time is showing as being correct. I'm also getting this Cron warning since I updated the system time a few days ago (copy below) which probably explains why this is happening, but I'm not sure how to fix it.

(For info I'm based in the UK, so it's probably something to do with daylight saving. Isn't there a way to get the system to handle this automatically, perhaps by synchronising with an external service?)

Can anyone help?

PHP Warning:  mktime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for 'GMT/0.0/no DST' instead in /var/www/vhosts/fieldsupport.net/httpdocs/inc/classes/BxDolTemplate.php on line 298

PHP Warning:  getdate(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for 'GMT/0.0/no DST' instead in /var/www/vhosts/fieldsupport.net/httpdocs/periodic/cron.php on line 127

PHP Warning:  mktime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for 'GMT/0.0/no DST' instead in /var/www/vhosts/fieldsupport.net/httpdocs/inc/classes/BxDolTemplate.php on line 298

Create a php.ini file in Dolphin's main directory:

[PHP]

date.timezone = America/New_York

Replace the timezone with something more appropriate: http://php.net/manual/en/timezones.php

In case php.ini doesn't work, change the file name to .user.ini (note that initial period) and see if that sticks.

Edit: From within Plesk, you can set the timezone on a per-domain basis. Go to Websites & Domains -> [domain] -> PHP Settings, and under the additional options at the bottom, enter:

date.timezone = America/New_York

Or, edit the main php.ini setting and it will be applied to all sites running on your sever.

Plesk doesn't play ball like that. However idiotic that may seem.