Freight inwards on PO and GRPO

We have set up the Freight section and ticked the "Stock/Fixed Assets" box for the "Transport Inwards" freight option

When we complete a PO with Freight charges on and convert to a GRPO, stock is correctly incremented by the cost of the goods and the freight. The credit for the Goods correctly goes to our allocation account "Goods Received Not Invoiced" but the credit for the expected freight invoice goes to "Variance Account" Please can you advise where in the GL determinations the GL account for the freight element is defined?

Many thanks