{
    "company": {
        "id": "12345",
        "name": "MyCompany",
        "contacts": [
            {
                "type":"phone",
                "value":"+1-345-567"
            },
            {
                "type":"email",
                "value":"mycompany@gmail.com"
            }
        ]
    },
    "employee": [
        {
            "name": "Bily",
            "salary": 56000,
            "married": true,
            "contacts": [
                {
                    "type":"phone",
                    "value":"+1-345-566"
                },
                {
                    "type":"email",
                    "value":"bily@gmail.com"
                }
            ]
        },
        {
            "name": "Lily",
            "salary": 56000,
            "married": true,
            "contacts": [
                {
                    "type":"phone",
                    "value":"+1-345-568"
                },
                {
                    "type":"email",
                    "value":"lily@gmail.com"
                }
            ]
        }
    ]
}

UPDATE tbl
SET jdoc = jsonb_set(jdoc, '{company,name}', "MyCompany Ltd."::jsonb, false);

UPDATE tbl
SET jdoc = jsonb_set(jdoc, '{company,contacts,1,value}'::text[], '"company@gmail.com"')
WHERE (jdoc #>> '{company,contacts,1,value}') = 'mycompany@gmail.com';