Hi Kerry, thanks for joining the Community. Please check the automated settings by navigating to the Cog > Account & settings > Advanced > Automation > See 'automatically apply credits'. This setting automatically applies credits to the next invoice you create for the same customer and can be turned off by toggling the slider to the left. If you need to un-apply a credit, you can do this by opening the invoice > click on '1 payment made' and then the date to open the payment > untick the credit(s) listed under 'outstanding transactions' (or select 'clear payment') and save.
