Another "what Kind Of Query Is This" Thread

I have a Customer table in an Accounts Receivable late-payments database that has very basic fields:

CustomerNumber, Name, BillToAddress1, BillToAddress2, City, State, Zip, Phone

As we get changes from new invoicing activity, I need the table to update the contact info. So, we get a spreadsheet each day with new invoicing activity, some of which will already have customers in our database. I need to capture any new addresses or other contact information to update my current records. We append the new info to the Invoices table, then need to grab the new addresses and update the Customer table.

I don't know why I don't know how to do this, as it seems so simple. Any help is greatly appreciated.