Match & return data across multiple sheets, multiple criteria

I am using this spreadsheet to track customer payments and send invoices. I have a master sheet named "Invoice". I enter customer payments on their separate sheets. I would like to use the master invoice sheet to choose a customer name and have their loan/payment information populate, rather than creating a new invoice for every customer.

I don't know how to return data based on multiple criteria in multiple sheets. I've attached my spreadsheet and added notes on the pages to better explain?

Please help!