From Invoice report it is possible to mark many invoices as paid or create credit invoices for many invoices.
1. Go to 'Reports>Accounting>Invoices'.
2. Search, for example set 'Invoice and payment date to' today to see all unpaid invoices today.
3. In top right corner click 'Select and pay for invoices' icon.
4. Select the invoices you want to pay for or create credit invoices for.
5. Click 'Pay'. (If you want to remove the selection you made to start over click 'Clear').
6. To create payment for the invoices you selected choose a payment method in the dropdown and click 'Apply'.
This will generate a payment and a receipt in the corresponding reservations and the invoices will be fully paid in invoice report.
7. To create credit invoices for the invoices you selected check 'Generate credit invoice for invoice' check box and click 'Apply'.
This will create credit invoices in the corresponding reservations and the invoices will be fully credited in invoice report.