If you have the Desktop program installed on your computer you can do unlimited returns with it. If you used the Online version last year it was only good for 1 return and 2018 is not longer available to do online. You need to use the Desktop program installed on your computer to do a prior year. Do you need to buy or download 2018 program again? You can buy 2018 here, https://turbotax.intuit.com/personal-taxes/past-years-products/
Since you mentioned 3 returns, are you doing a Canada return?
