After you file

I am a Mac CD user and I found this TurboTax link very helpful https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return-in-the-turbotax-cd-download... ; however, I was stuck at Step 4: "You should now be working inside the copy you'll be amending. Inside your program, search for amend and then click the Jump to link." 

It turned out this Step 4 should be something like:

4.1 open your 2018 program, under EasyStep option menu, select "SearchTopic" option

4.2 type in "amend", then you will see the proper help pop up on the screen.