If you have filed you have to wait and see if the IRS accepts or rejects your return.  If they reject it you can fix  it and resend it.

You should not change or add anything until your original return is accepted (if they reject it you can fix it and resend it) and fully processed and you get the first refund or pay the tax due.  Then you can amend it.  Do not enter or change anything until after you start the amended return.   If you have added or changed your return you need to take out any changes and put your return back to the way it was when you originally filed it.  

Amended returns can only be MAILED not efiled.  How to amend 2017
https://ttlc.intuit.com/questions/4252298-how-do-i-amend-a-2017-return-in-turbotax

How to amend all years
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed

You will still get the first refund or need to pay the original tax due.  Then the amended return is only for the difference you get back or owe.  In fact you should not even amend until the first return has fully processed and you get the first refund or your tax due payment has cleared.  And make sure the original refund or tax paid shows up on the amended return.  You can confirm this by printing your amendment and looking at the 1040X. Line 18 should be your original refund amount and line 22 should be your additional refund.  If you paid on your original return it will be on line 16.  If there is an amount owed with the amendment, it will be on line 20.