The difference you are seeing here is because QuickFile calculates an exchange rate for the invoice and payment separately. Exporting a list of invoices or viewing an invoice in general will not show you the exchange rate associated with the payment. The difference allows you to calculate currency loss/gains on your accounts, i.e. you raise an invoice at one time (and one specific rate) and it’s paid at a later time (with a different rate).
For any given invoice you can see the exchange rate in the invoice editor. It is this rate that will show on the invoice export.
To see the exchange rate applied to the payment, click the payment link on the invoice preview screen.
On the payment preview you should be able to see the rate applied.
To get a list of exchange rates for the actual payments you would need to go to Sales >> Payments and export this payment list there.
Hope that helps, please let me know if you need any further clarification.