If you are using the Online version, you will have to do a new, separate online account (with a different user ID) for each federal return you want to prepare and purchase for each (if you need to use a paid version of the online software). If you do another return under the same username you did your own return, it will override the one you already filed and lose everything for that return. It's always been this way online.
You can still use your same email address (for up to 5 online accounts) if you want to get notifications, but the username must be a new one for each online account you create.
The CD/Download (desktop version) product is a better overall value for people who prepare tax returns for their friends and family. This one will allow you to prepare and print unlimited federal returns and e-file up to five at no extra cost. You can find the desktop versions here https://turbotax.intuit.com/personal-taxes/cd-download/
Does this mean 5 separate files total? Or 5 separate files each year?
Each year is separate. You have to use a separate program for each year. Online is only good for the current year. Online is only good for 1 return per account. But you can use the same email address for 5 accounts. How to start another return in the Online version
Or if you buy the Desktop CD/Download program you can do unlimited returns for one year. And efile 5 current year returns. You can print and mail any more.
To do prior year returns you have to buy theDesktop programs here. They only sell the last 3 years. You have to mail prior year returns.
https://turbotax.intuit.com/personal-taxes/past-years-products/
You will need a full Windows or Mac to install it on.
Thank you for the quick and helpful response. Just to clarify though, if I buy the program version for my Windows computer, will my family members and I be able to use it year after year?
You can all use it but only for one year. You have to buy a new program for each year. You can install it on 5 computers you own.
You can buy 2019 Desktop program here or look in the stores for sales. https://turbotax.intuit.com/personal-taxes/cd-download/
The CD has both Windows and Mac programs on it. If you buy the download you need to buy the right one. And by the way, you can buy any Desktop version. All the Desktop programs have the same forms. You just get more help and guidance in the higher versions.