Let's use this credit to deduct the total bill due amount. You can follow these steps:
Go to the +New button and select the Supplier credit.
Select a Supplier and enter the required info.
Tap Save and close.
Once you recorded a bill, we can process a payment. Choose Pay bills from the +New button. Then, you can apply the credit in the Credit Applied column.
I've included these articles for your reference. These will show you the correct way of tracking bills and expenses.