I’m using Zabbix 4.4.3 (latest version), installed using RedHat packages, and the timezone was showing UTC and I needed to change it to my local timezone (EST).

In dozens of different sites I found instructions explaining to configure timezone in php.ini (for me it was in /etc/php.ini) like this:

[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
;date.timezone =
date.timezone = "America/New_York"

I restarted the services and it wasn’t still working. Although the Local Clock works, the Problems Timeline was still showing UTC timezone:

So I decided to put directly this configuration in the PHP application (Zabbix). I found the UI configuration to be in /etc/zabbix/web/zabbix.conf.php, and just had to add this line:

date_default_timezone_set('America/New_York');

And now it works (no need to restart the services):

PS: Somewhere I read thatI should configure /etc/apache2/conf-available/zabbix-frontend-php.conf, but I couldn’t find this file anywhere in my RedHat installation.