Credit Balance Applied to New and Future Invoices

[Sleeslag]

So I am totally new to this software and basically accounting. I may have did this wrong from setup but I am hoping for some guidance.

 

So I manage a water club that people pay me monthly. When I created the customer accounts some of them had extra money on their account. So for example John Doe has a -$20.00 balance.

 

Then I setup a $5.00 item that bills a recurring invoice monthly. So John has a starting balance of -$20.00, the recurring billing which began 7/1 was $5.00. John's current balance is now -$15.00

 

His invoice is marked unpaid. Is there a way to apply the negative balances to the invoices?

 

I frequently get payments above what the invoice will be. So people pay for a few months in advance. So is there a better way to reflect these monthly charges and apply them to future invoices?