I'm assuming you are using the Desktop installed program?
Transferring 2018 is ok but won't give you what you want. You need to look at a 2018 pdf file of your return. If you only have the data file ending in .tax2018 you need to open it in the 2018 program.
You can only transfer 2018 into a new blank 2019 return so it's not going to affect your existing 2019 return. Have you saved your 2019 return? Save it again with another name so you have extra copies. Go up to File-Save As or Duplicate.
