Denver Research

Products can be rented or sold.  In the Product Edit window, were you create new products, change the Sell to one of the rental options.  This will allow you to set a rental price.  So, if you have a rent and selling price the software will ask the cashier to select renting or selling.

OK, we added some smarts to the Qty button.  It now works with kits and parts a little smarter.  I'm sending you an update.  You may want to consider updating to the current version.  In your post you said in an older version the Qty button worked with parts.  I don't think so.  We had to add new code to deal with parts.

Are you applying the payments to the invoices?  If you only add the payments to a customer account but do not apply it to a invoice, then those invoices will be listed as Not Paid, even though the customers balance will be zero.

It's shown in the window title bar

Umm, read the post above this?

There are two receipts.  A receipt that has the items purchased on it and a payment receipt.  The blank Tip line for the customer to fill in only shows up on payment receipts (restaurant version only).

Sorry, there is no option to add fields to the invoice.

The version 13 you have already prints the customer address and Message on the packing list.