Hi @endo-consultants,
I'd be glad to assist you with tracking your cash expenses. To do it, you'll have to manually add the expense from the Transactions page.
Here's how:
- Go to Transactions.
- Select the Add transaction drop-down.
- Enter the expense details and make sure to Select a category for your cash transactions.
- Click Save.
Below is the image of how it looks like.

Here's a guide to learn more about adding transactions: Manually add transactions in QuickBooks Self-Employed.
I'm also attaching the link below in case you need help with other tasks in QuickBooks Self-Employed (QBSE). It has topics with articles that'll help you along the way.
Please don't hesitate to comment below if you still have questions or concerns with cash transactions. I'm more than happy to answer them for you. Take care and have a great day ahead.