From version 5.13 the setting of time zone has been moved to database table qu_g_settings.
In downloadable licenses, you can define your own timezone as the default timezone matches Los Angeles (USA) time. To do so, edit your accounts/settings.php file and add this line of code there: TIMEZONE=America/Los_Angeles insert a row into table qu_g_settings with name="TIMEZONE" and value of a valid timezone name.
Changing timezone of an existing LiveAgent installation is discouraged. The setting affects the values which are saved in database and how the existing values from database are interpreted. the values are always converted to local timezone before being displayed in agent panel, in other words agents and admins always see values in their local timezone. If you change timezone setting of an existing installation, all values stored in database will be interpreted as being in the set timezone.
Here's a list of all available timezones:
Africa
| Africa/Abidjan |
Africa/Accra |
Africa/Addis_Ababa |
Africa/Algiers |
Africa/Asmara |
| Africa/Asmera |
Africa/Bamako |
Africa/Bangui |
Africa/Banjul |
Africa/Bissau |
| Africa/Blantyre |
Africa/Brazzaville |
Africa/Bujumbura |
Africa/Cairo |
Africa/Casablanca |
| Africa/Ceuta |
Africa/Conakry |
Africa/Dakar |
Africa/Dar_es_Salaam |
Africa/Djibouti |
| Africa/Douala |
Africa/El_Aaiun |
Africa/Freetown |
Africa/Gaborone |
Africa/Harare |
| Africa/Johannesburg |
Africa/Kampala |
Africa/Khartoum |
Africa/Kigali |
Africa/Kinshasa |
| Africa/Lagos |
Africa/Libreville |
Africa/Lome |
Africa/Luanda |
Africa/Lubumbashi |
| Africa/Lusaka |
Africa/Malabo |
Africa/Maputo |
Africa/Maseru |
Africa/Mbabane |
| Africa/Mogadishu |
Africa/Monrovia |
Africa/Nairobi |
Africa/Ndjamena |
Africa/Niamey |
| Africa/Nouakchott |
Africa/Ouagadougou |
Africa/Porto-Novo |
Africa/Sao_Tome |
Africa/Timbuktu |
| Africa/Tripoli |
Africa/Tunis |
Africa/Windhoek |
|
America
| America/Adak |
America/Anchorage |
America/Anguilla |
America/Antigua |
America/Araguaina |
| America/Argentina/Buenos_Aires |
America/Argentina/Catamarca |
America/Argentina/ComodRivadavia |
America/Argentina/Cordoba |
America/Argentina/Jujuy |
| America/Argentina/La_Rioja |
America/Argentina/Mendoza |
America/Argentina/Rio_Gallegos |
America/Argentina/San_Juan |
America/Argentina/San_Luis |
| America/Argentina/Tucuman |
America/Argentina/Ushuaia |
America/Aruba |
America/Asuncion |
America/Atikokan |
| America/Atka |
America/Bahia |
America/Barbados |
America/Belem |
America/Belize |
| America/Blanc-Sablon |
America/Boa_Vista |
America/Bogota |
America/Boise |
America/Buenos_Aires |
| America/Cambridge_Bay |
America/Campo_Grande |
America/Cancun |
America/Caracas |
America/Catamarca |
| America/Cayenne |
America/Cayman |
America/Chicago |
America/Chihuahua |
America/Coral_Harbour |
| America/Cordoba |
America/Costa_Rica |
America/Cuiaba |
America/Curacao |
America/Danmarkshavn |
| America/Dawson |
America/Dawson_Creek |
America/Denver |
America/Detroit |
America/Dominica |
| America/Edmonton |
America/Eirunepe |
America/El_Salvador |
America/Ensenada |
America/Fort_Wayne |
| America/Fortaleza |
America/Glace_Bay |
America/Godthab |
America/Goose_Bay |
America/Grand_Turk |
| America/Grenada |
America/Guadeloupe |
America/Guatemala |
America/Guayaquil |
America/Guyana |
| America/Halifax |
America/Havana |
America/Hermosillo |
America/Indiana/Indianapolis |
America/Indiana/Knox |
| America/Indiana/Marengo |
America/Indiana/Petersburg |
America/Indiana/Tell_City |
America/Indiana/Vevay |
America/Indiana/Vincennes |
| America/Indiana/Winamac |
America/Indianapolis |
America/Inuvik |
America/Iqaluit |
America/Jamaica |
| America/Jujuy |
America/Juneau |
America/Kentucky/Louisville |
America/Kentucky/Monticello |
America/Knox_IN |
| America/La_Paz |
America/Lima |
America/Los_Angeles |
America/Louisville |
America/Maceio |
| America/Managua |
America/Manaus |
America/Marigot |
America/Martinique |
America/Mazatlan |
| America/Mendoza |
America/Menominee |
America/Merida |
America/Mexico_City |
America/Miquelon |
| America/Moncton |
America/Monterrey |
America/Montevideo |
America/Montreal |
America/Montserrat |
| America/Nassau |
America/New_York |
America/Nipigon |
America/Nome |
America/Noronha |
| America/North_Dakota/Center |
America/North_Dakota/New_Salem |
America/Panama |
America/Pangnirtung |
America/Paramaribo |
| America/Phoenix |
America/Port-au-Prince |
America/Port_of_Spain |
America/Porto_Acre |
America/Porto_Velho |
| America/Puerto_Rico |
America/Rainy_River |
America/Rankin_Inlet |
America/Recife |
America/Regina |
| America/Resolute |
America/Rio_Branco |
America/Rosario |
America/Santiago |
America/Santo_Domingo |
| America/Sao_Paulo |
America/Scoresbysund |
America/Shiprock |
America/St_Barthelemy |
America/St_Johns |
| America/St_Kitts |
America/St_Lucia |
America/St_Thomas |
America/St_Vincent |
America/Swift_Current |
| America/Tegucigalpa |
America/Thule |
America/Thunder_Bay |
America/Tijuana |
America/Toronto |
| America/Tortola |
America/Vancouver |
America/Virgin |
America/Whitehorse |
America/Winnipeg |
| America/Yakutat |
America/Yellowknife |
|
|
|
Antarctica
| Antarctica/Casey |
Antarctica/Davis |
Antarctica/DumontDUrville |
Antarctica/Mawson |
Antarctica/McMurdo |
| Antarctica/Palmer |
Antarctica/Rothera |
Antarctica/South_Pole |
Antarctica/Syowa |
Antarctica/Vostok |
Arctic
| Arctic/Longyearbyen |
Asia
| Asia/Aden |
Asia/Almaty |
Asia/Amman |
Asia/Anadyr |
Asia/Aqtau |
| Asia/Aqtobe |
Asia/Ashgabat |
Asia/Ashkhabad |
Asia/Baghdad |
Asia/Bahrain |
| Asia/Baku |
Asia/Bangkok |
Asia/Beirut |
Asia/Bishkek |
Asia/Brunei |
| Asia/Calcutta |
Asia/Choibalsan |
Asia/Chongqing |
Asia/Chungking |
Asia/Colombo |
| Asia/Dacca |
Asia/Damascus |
Asia/Dhaka |
Asia/Dili |
Asia/Dubai |
| Asia/Dushanbe |
Asia/Gaza |
Asia/Harbin |
Asia/Ho_Chi_Minh |
Asia/Hong_Kong |
| Asia/Hovd |
Asia/Irkutsk |
Asia/Istanbul |
Asia/Jakarta |
Asia/Jayapura |
| Asia/Jerusalem |
Asia/Kabul |
Asia/Kamchatka |
Asia/Karachi |
Asia/Kashgar |
| Asia/Katmandu |
Asia/Kolkata |
Asia/Krasnoyarsk |
Asia/Kuala_Lumpur |
Asia/Kuching |
| Asia/Kuwait |
Asia/Macao |
Asia/Macau |
Asia/Magadan |
Asia/Makassar |
| Asia/Manila |
Asia/Muscat |
Asia/Nicosia |
Asia/Novosibirsk |
Asia/Omsk |
| Asia/Oral |
Asia/Phnom_Penh |
Asia/Pontianak |
Asia/Pyongyang |
Asia/Qatar |
| Asia/Qyzylorda |
Asia/Rangoon |
Asia/Riyadh |
Asia/Saigon |
Asia/Sakhalin |
| Asia/Samarkand |
Asia/Seoul |
Asia/Shanghai |
Asia/Singapore |
Asia/Taipei |
| Asia/Tashkent |
Asia/Tbilisi |
Asia/Tehran |
Asia/Tel_Aviv |
Asia/Thimbu |
| Asia/Thimphu |
Asia/Tokyo |
Asia/Ujung_Pandang |
Asia/Ulaanbaatar |
Asia/Ulan_Bator |
| Asia/Urumqi |
Asia/Vientiane |
Asia/Vladivostok |
Asia/Yakutsk |
Asia/Yekaterinburg |
| Asia/Yerevan |
|
|
|
|
Atlantic
| Atlantic/Azores |
Atlantic/Bermuda |
Atlantic/Canary |
Atlantic/Cape_Verde |
Atlantic/Faeroe |
| Atlantic/Faroe |
Atlantic/Jan_Mayen |
Atlantic/Madeira |
Atlantic/Reykjavik |
Atlantic/South_Georgia |
| Atlantic/St_Helena |
Atlantic/Stanley |
|
|
|
Australia
| Australia/ACT |
Australia/Adelaide |
Australia/Brisbane |
Australia/Broken_Hill |
Australia/Canberra |
| Australia/Currie |
Australia/Darwin |
Australia/Eucla |
Australia/Hobart |
Australia/LHI |
| Australia/Lindeman |
Australia/Lord_Howe |
Australia/Melbourne |
Australia/North |
Australia/NSW |
| Australia/Perth |
Australia/Queensland |
Australia/South |
Australia/Sydney |
Australia/Tasmania |
| Australia/Victoria |
Australia/West |
Australia/Yancowinna |
|
|
Europe
| Europe/Amsterdam |
Europe/Andorra |
Europe/Athens |
Europe/Belfast |
Europe/Belgrade |
| Europe/Berlin |
Europe/Bratislava |
Europe/Brussels |
Europe/Bucharest |
Europe/Budapest |
| Europe/Chisinau |
Europe/Copenhagen |
Europe/Dublin |
Europe/Gibraltar |
Europe/Guernsey |
| Europe/Helsinki |
Europe/Isle_of_Man |
Europe/Istanbul |
Europe/Jersey |
Europe/Kaliningrad |
| Europe/Kiev |
Europe/Lisbon |
Europe/Ljubljana |
Europe/London |
Europe/Luxembourg |
| Europe/Madrid |
Europe/Malta |
Europe/Mariehamn |
Europe/Minsk |
Europe/Monaco |
| Europe/Moscow |
Europe/Nicosia |
Europe/Oslo |
Europe/Paris |
Europe/Podgorica |
| Europe/Prague |
Europe/Riga |
Europe/Rome |
Europe/Samara |
Europe/San_Marino |
| Europe/Sarajevo |
Europe/Simferopol |
Europe/Skopje |
Europe/Sofia |
Europe/Stockholm |
| Europe/Tallinn |
Europe/Tirane |
Europe/Tiraspol |
Europe/Uzhgorod |
Europe/Vaduz |
| Europe/Vatican |
Europe/Vienna |
Europe/Vilnius |
Europe/Volgograd |
Europe/Warsaw |
| Europe/Zagreb |
Europe/Zaporozhye |
Europe/Zurich |
|
|
Indian
| Indian/Antananarivo |
Indian/Chagos |
Indian/Christmas |
Indian/Cocos |
Indian/Comoro |
| Indian/Kerguelen |
Indian/Mahe |
Indian/Maldives |
Indian/Mauritius |
Indian/Mayotte |
| Indian/Reunion |
|
|
|
|
Pacific
| Pacific/Apia |
Pacific/Auckland |
Pacific/Chatham |
Pacific/Easter |
Pacific/Efate |
| Pacific/Enderbury |
Pacific/Fakaofo |
Pacific/Fiji |
Pacific/Funafuti |
Pacific/Galapagos |
| Pacific/Gambier |
Pacific/Guadalcanal |
Pacific/Guam |
Pacific/Honolulu |
Pacific/Johnston |
| Pacific/Kiritimati |
Pacific/Kosrae |
Pacific/Kwajalein |
Pacific/Majuro |
Pacific/Marquesas |
| Pacific/Midway |
Pacific/Nauru |
Pacific/Niue |
Pacific/Norfolk |
Pacific/Noumea |
| Pacific/Pago_Pago |
Pacific/Palau |
Pacific/Pitcairn |
Pacific/Ponape |
Pacific/Port_Moresby |
| Pacific/Rarotonga |
Pacific/Saipan |
Pacific/Samoa |
Pacific/Tahiti |
Pacific/Tarawa |
| Pacific/Tongatapu |
Pacific/Truk |
Pacific/Wake |
Pacific/Wallis |
Pacific/Yap |
source (https://php.net/manual/en/timezones.php)