I work with several homeowner's associations. You can create an invoice for each unit and make it recurring in QBO (memorized in QB Desktop). They can have different amounts due. If the amount changes monthly, select to remind you to send them so you can adjust them. If the amounts due are different for each homeowner but the same amt. every month, you can schedule the invoices to populate.
I have QBO set up for rental properties that my husband and I own. We are loving the payment system in QBO and it has effectively allowed us to email the tenants on the first of the month with a payment link. Most (about 85% now) are paying us with ACH method, a few with a credit card. But it has reduced our collections on late payers significantly. We are also "reminding" tenants if they forget to pay us on the first. I remind the few stragglers each Friday that late charges are in affect.
As for the running balance, you can send them a statement. I also use the account summary on the invoice so that it shows the last invoice, payment, and any outstanding balance. That has also helped with collection.