Hello, @melissasupler-gm

You'd want to set up your vendor's bank account manually or invite him or her to enter it in QuickBooks. This way, you can pay a vendor through Bank Transfer or ACH. I can guide you in doing so.

Here's how to add your vendor's bank account:

1. Navigate to the Pay bills online.
   • Go to the + New., then choose Pay Bills Online.
   • Choose the Bill Pay Online dashboard widget.
   • Select the Expense tab then click Pay Bills Online.
2. If the vendor has an open bill, select Set up Bank Transfers within the same line as the Payee. 
3. Select Enter vendor's bank account info,  then click Next.
4. Enter the vendor's bank account information.
5. Click Save.

You can browse this article for more detailed instructions: Set up a bank transfer to a vendor.

Also, if you want to track bill payment in QuickBooks Online that was paid via your bank's website, EFT, ATM, or debit card, you can check this article: Record a bill payment by EFT, ATM card, or debit card.

I'm always around if you have any other questions about recording vendor-related transactions. Feel free to leave a comment below. Have a wonderful day.