We will add port customization in the next version for PostgreSQLDataSource. Meanwhile you could either:

1 . Open the file koolreport/core/src/datasources/PostgreSQLDataSource.php and replace the following lines:

        $host = Util::get($this->params, "host", "");//host\instanceName
        $username = Util::get($this->params, "username", "");
        $password = Util::get($this->params, "password", "");
        $dbname = Util::get($this->params, "dbname", "");
        $connString = "host=$host dbname=$dbname user=$username password=$password";

with these:

        $host = Util::get($this->params, "host", "");//host\instanceName
        $port = Util::get($this->params, "port", 5432);
        $username = Util::get($this->params, "username", "");
        $password = Util::get($this->params, "password", "");
        $dbname = Util::get($this->params, "dbname", "");
        $connString = "host=$host port=$port dbname=$dbname user=$username password=$password";

Then customize port like this:

    "postgresql"=> [
                    'host' => '127.0.0.1',
                    'port' => 5433,
                    'username' => 'postgres',
                    'password' => 'toto',
                    'dbname' => 'test',
                    'class' => "\koolreport\datasources\PostgreSQLDataSource" 
                ],

2 . Use PDODataSource in which you could customize port in its connection string.

Let us know if you have more question. Thanks!