You may have subscribed to the incorrect version of QuickBooks Self-Employed. The currency sign is one of the reasons that you have the UK version of it and changing it is not possible.
With this, you can consider canceling your current account and register for the correct version. Let me guide you with the correct steps.
To start with, here's how you can cancel your current account:
Once done, you can start subscribing to the correct account by following the steps below:
Additionally, I've got you this helpful article to understand more about how you work well with business with your new self-employed account: QuickBooks Self-Employed Overview.
If you have any other questions, please let me know by leaving any comments below. I'll be here to help. Stay safe!
QBSE only supports a single currency. You have to use QBSE US version to have the USD currency.
Otherwise you may open a virtual bank account at TW to accept multi currency payments and utilize the bank feeds.