Currently, QuickBooks Self-Employed doesn't offer a feature to track your accountant's sign-in or activity history, Jwhitaker.
While you can't view a login history, the easiest way to confirm if they've accessed your files is to ask them directly.
You can also check for changes in your data. Adjustments like categorized transactions, added receipts, or other updates would be visible in your account. Comparing the current state of your books to a few weeks ago can help you identify any alterations.
We'll be right here if you need more clarification or if you have other questions.