In the administration section, if you go to tools, Host Tools, and select PHP info, you get an overview of your PHP settings, incl the location of the PHP.ini file that is in use (Loaded Configuration File).
In the PHP.ini file add the following line:
date.timezone = "Europe/Madrid"
When done, you need to restart the Apache service for this new setting to become active
Please be aware that PHP executed via crons might use a different PHP.ini file than PHP executed via your webserver
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