Supplier credits not visible when making payments

Hi there, @sharonmcnulty.

Thanks for reaching out to the Community for support. I'm happy to lend a hand so that we can find the credits.

A vendor credit is use in QuickBooks Online to either record returns or refunds from vendors. Since these are missing, it's possible that you enable the Automatically apply bill payments. This setting automatically applies the payments to the oldest existing bill. 
  
Here's how to check:

1. Go to the Gear icon and select Account and Settings.
2. Click Advanced tab.
3. Go to Automation and turn off Automatically apply bill payments. 
4. Tap Save, then Done.

I've added some screenshots below for your visual reference:

Once done, you can run a report with vendor totals. This way, it will show all the payments made to vendors. Thus, we can check if the credit was applied to other bills.

Here's how:

1. On the left menu, select Reports.
2. Enter the report name as Transaction List by Date.
3. Select Transaction List by Date then, select a Report period.
4. For Group By, select Vendor.
6. Select Customize. 
7. Filter Transaction Types and select Run Report.

8. Click Save customization, then select Save.

Additionally, it is also possible that you entered a regular check instead of a credit. That being said, I recommend using Accounts Payable so it will show to Pay bills.

For more reference, I've attached a link you can use to apply vendor credits. 

Please stay in touch if you need more help with handling vendor credits in QBO. I am always here to assist you. Have a great day.