if you install 2015-2018 and then open the .tax file for any of those years, you will change the results because updates are no longer available. you can exit without saving to preserve the file as it was. if you need pdf's yo could use a service like Taxprinter but note the fee. however by filing form 4506 with the iRS you should be able to get copies of 2015-2018
https://www.taxprinter.com/
irs
https://www.irs.gov/pub/irs-pdf/f4506.pdf $43/return no state
or use 4506-T which is a transcript not a copy of the return like what you get with the above - free
https://www.irs.gov/pub/irs-pdf/f4506t.pdf
