Hi Cityconect,
Currently, adding a customer currency profile under one group isn't possible. You'll have to create a new profile for your customers for each of the currency and assign a slightly different name to easily track the customer.
- Click Sales on the left menu.
- Go to the Customers tab.
- Click New customer.
- Enter the necessary information about your customer.
- Click Save.
You can repeat the steps above if you want to assign a different currency to your customer.
I'll also pass this along to our product team to let them know if your business needs.
Once done, in case you want to create an account for each of your customer's currency, check this article for more information: Create Subaccounts In Your Chart of Accounts in QuickBooks Online.
Please let us know if you have any concerns about QuickBooks. We're always right here to assist you.