Thank you for this @JessT .
However, please can you advise the best way to input these transactions when the funds are received to a USD bank account? It is great that I can do this in principle however, it is not what actually happens. As we are not able to receive USD into our actual bank account (as against the QB one), we receive the money into our USD bank account and, then once we have received the funds (checked via online banking), we transfer it to our GBP account. So, these are transactions which actually happen via the banks rather than just the way it has been done in QB.
Many thanks.
You're welcome, E21J, and thank you for the additional details.
When you transfer the funds from your USD bank account to your GBP bank account, please be sure to choose US Dollar as the transfer currency. Then, you will enter the USD amount and the exchange rate at that time. This will zero out the balance in your USD account.

Please let me know if you have other questions.