In this example, I will be allocating a US dollar receipt to a US dollar invoice on an account with the home currency in UK Pound Sterling. 

Step 1. 

Navigate to Sales > Money in.

Step 2.

Fill in the details of the payment received. Make sure to use the appropriate bank account and FX rate. Hit the Confirm button to complete.

The system will automatically adjust the FX rate based on the payment date. These conversion rates are updated from

Step 3.

Once the payment is confirmed, you will be redirected to the allocation menu.

Change the currency in the drop-down box and select the appropriate payment (if there is more than one). Type in the amount to be allocated to the invoice in the Allocate payment box and hit the Allocate button to complete.