How do I change the currency on an invoice

It's great having you here in the QuickBooks Community, @mag_e003. 

Changing the currency on an invoice in QuickBooks Self-Employed (QBSE) isn't currently possible. I'm here to help share alternative options at hand. 

For now, you can consider manually converting the foreign amount to US dollars. Then, enter the amount on the invoice. 

Alternatively, consider upgrading to QuickBooks Online (QBO) Essentials, Plus, or Advanced which supports multicurrency features. Multicurrency allows you to pay and get paid in the foreign currencies of customers, vendors, or bank accounts. If you choose this option, you can follow these steps: 

First, download all your work from QuickBooks Self-Employed so you can have a backup copy.

1. Go to Reports.
2. From the Tax details section, select a tax year.
3. Select Download.
4. Download a report for each year you have in QuickBooks.
5. Repeat these steps for your Profit and Loss, Mileage Log, and Receipts.

Once done, copy your data to QBO. Just a heads up, there's no way to return to QBSE after this process: 

1. Go to the Gear icon, then from the Profile column, select Upgrade.
2. Select Choose plan on the one that you prefer.
3. Review the changes in features, then select Sounds good.
4. If you want to copy your data to QuickBooks Online, select Bring my data. If not, select Start Fresh.
5. If you choose to bring your data, follow the steps to categorize open transactions and mark the paid invoices.
6. Review the summary of data that you'll move to QuickBooks Online.
7. Select Continue, then To QuickBooks Online!
8. Double-check your payment method, then select Change plan. If you need to change payment method, select Edit.
9. Answer or confirm ‌a few details about your business to start using QuickBooks Online.

For more detailed steps, refer to this article: Switch from QuickBooks Self-Employed to QuickBooks Online. 

If you need to categorize transactions after this, let me add this article as a guide: Categorize transactions in QuickBooks Self-Employed. 

We'll be here in the Community if you have further concerns about changing currency in QBSE. We'll do our best to assist.