If whatever you did to amend your 2018 return did not result in a 1040X, then you amended incorrectly. We cannot see what you did, or what instructions you did not follow. But you have to work from the original 2018 return EXACTLY as it appeared before you made any changes to it. Then you follow the instructions to amend it. Your amended return will have to be printed, signed and mailed. It cannot be e-filed.
https://ttlc.intuit.com/questions/2566895-what-does-it-mean-to-amend-a-return
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed?jump_to=answer_3288565