I appreciate your posting your bank matching concern in QuickBooks Self-Employed (QBSE), Caroline. Let me address this inquiry of yours.
First, I'd like to know what transactions you're trying to match in your QBSE account. Or are you trying to match your bank statements outside of QBSE?
Know that in QBSE, there are no matching features available. You can only categorize your accounts according to what type they are under - Business or Personal transactions. Split if it's under the two.
The Matching feature is only available in QuickBooks Online (QBO) subscription, which helps the transactions you've downloaded from your bank to coincide with the transactions in your QBO account for the organization and avoid duplication.
You can see this article as a reference for categorizing your transactions in QBSE and the matching of transactions in QBO:
Giving me further information about what you're trying to match your transactions within your QBSE can narrow down the specificity of the steps to resolve the issue.
Let me know if you need further help with your transactions in QBSE, Caroline. I'll be here to assist you at any time. Have a great day ahead!