Is there any way I can set up an automatic invoicing system for my clients

I understand the importance of setting up invoices automatically in QuickBooks Self-employed (QBSE), @maiphuongtran-30.

Let me share some information about this. 

The automatic invoicing feature is unavailable for QBSE. If it's necessary for your business, you can subscribe to a QuickBooks Online (QBO) company.

If you decide to proceed with QBO, refer to this article: How to create a recurring invoice and manage recurring transactions. It's a walkthrough on how you can create recurring transactions in QBO. 

Otherwise, refer to this article: Recurring Payments. It's an in-depth guide on how you can create recurring transactions in QBDT.

Feel free to tag me in the comments below if you have additional questions about invoices. I'll get back to you as soon as I can.