No you cannot change prior year info that transferred into the program and is shown on the summary screens ... all you can do is change anything that may need to be corrected as you run across it if it is no longer correct. And as you said it really doesn't matter since the IRS/STATE do not see this info ... it is for your use only. If you had amended the 2017 return BEFORE filing the 2018 then it would have been correct.
