Can anyone tell me which they have found the best way to use online bill pay, via paper check or electronic voucher? Thanks for any help?

If you scheduled the payment far enough in advance, and if the pay date is in advance of the due date, contact the processor and complain asking them to pay any late fees

I can share with you some details about paying your bills online, @bcookmanteo-gmai.

Using Online Bill Pay lets you pay your bills directly in QuickBooks Online (QBO). This makes it easier for our users to make payments within their QBO accounts.

In regards to paying your bills via a paper check or electronic voucher, I recommend discussing it with your vendor to know which payment method they prefer.

Additionally, I'm adding these resources that you can use to learn more about how Online Bill Pays work: 

• Pay bills in Online Bill Pay 
• What is Online Bill Pay?

Furthermore, I'd propose contacting the Bill Pay support team. This way, one of their agents can look into your account in a secure space and check the reason for the late payment. You can get their contact information from their profile in the Apps menu.

Lastly, I'm attaching these links that serve as your guide in case you need to refund and enter a credit for your vendor:

• Enter a refund from a vendor 
• Applying vendor credits

I'm just a few clicks away if you have additional questions about paying your bills in QBO. Feel free to add the details in your reply and I'll get back to you as soon as possible. Have a dazzling day ahead and always keep safe!