Hi @Sarah_Brice
The manual adjustment would need to be made directly on the VAT return as per the guide here. The VAT return calculations in QuickFile are driven by sales and purchase invoices and don’t directly pickup journals.
If you use the method described in the link it will include the adjustment on the auto-generate VAT return journal. You can view and modify this as needed, the journal will be visible in the main list (Reports >> Journals).
Please let me know if I can be of further assistance.