Hello, bbeautifullkme-g.
I'll guide you on how you can mark your transactions as paid in QuickBooks Self-Employed.
I take it that you're referring to your invoices. In this case, you can mark them as paid by going to the Invoices page. Here's how:
- Go to the Invoices page.
- Find the invoice you want to mark as paid.
- Click the arrow icon under ACTION.
- Select Mark as paid.

It should be noted that invoices are just for recording purposes only. They won't affect your income taxes until you've recorded their payments in the Transactions page.
To record the payments, go to the Transactions page then click the Add transactions button. Enter the details of the invoice payment, then click Save. If you have a connected bank account, you'd simply want to categorize them as income.
However if you're referring to bills, QuickBooks Self-Employed doesn't have the Bill tracking feature.
You'll want to record your expenses manually through the Transactions page (either manually or through your connected bank account).
Ready to take care of your estimated taxes? Feel free to use this article as a guide: Pay federal estimated quarterly taxes in QuickBooks Self-Employed.
I can share several guides and details if you have more questions about the Self-Employed platform. Just use this thread, and I'll get back to you as soon as possible. I'll see you around real soon.