I want to do my 2017 and 2018 taxes. If I buy the old 2017 software would I then be able to easily figure out investments etc. or should I use the 2018 program for both?

I have started both years on TT. it tells me to upgrade to amend the 2017. After 90 minutes of attempting to find the place to upgrade I am giving up. (I did read the instructions, over and over but they do not work). 

My goal is to get the ease of TT for the 2017 taxes. Would be better to buy the old version to do that? What is my best course of action to do both years? I can pay for both years' software if I am getting the benefits of doing things like feeding the data in directly from investment account. Do I get that for both years if I buy the 2018 Home and Business? Or do I get it only for 2018? Do I get it for 2017 if I buy the 2017 Home and Business? Can that be upgraded to do 2018 as well?