If using a personal bank account for small business. How do I categorise personal expenses

Hi darrindodson661-,

You can setup a personal bank account and use it as a payment type when recording your personal expenses in QuickBooks Online. Let me guide you on how to set it up. 

1. On the Accounting tab, select Chart of Accounts.
2. Select New.
3. On Account Type, select Cash and cash equivalents.
4. Then select the closest Detail Type.
5. Enter Name of the account and select Save and close. 

Also, you can set it up as an Owner's equity and use it in a few different ways. For more detailed information, you can check on this article for your future reference: Mixing business and personal funds. 

Let me know if you have any other questions and I'd be glad to help. Have a nice day!