I don't know if you have an answer yet or not elsewhere but the settings for your printing are stored in the Simply database. So reinstalling the program would not alter that. If you had templates on your computer before, you have them now and you should be able to just hit print and the same format will be used. It sounds like you also change the printer settings in your company file for your userid.
Invoice.rpt is the basic invoice for printing on blank paper. You can use it to start modifying for your own design. Make sure you change the filename before you are done so you don't overwrite the original. The design of the template is responsible for placing the fields from the csv files on the final page.
The basic idea is that Simply exports data to the csv files. Then it tells the Crystal template where the files are and to print. The Crystal template reads the data, formats it and prints.