I think I accidentally filed 1040ez instead of 1040a. I have a dependent and get child tax credit. How can I go back to change to 1040a?

[ChristyW]

You are correct, you should at least have a Form 1040A if you have a dependent. TurboTax will choose and file the return applicable for your situation. To see the 1040 form that was filed and review any applicable credits sign into your return, and select Download/print return. 

If after reviewing your download, you are sure you need to make changes, you will need to wait for your return to be accepted or rejected. If it is rejected, great, you can fix it and refile. If it is accepted you will need to file an amendment.

How do I amend my 2017 TurboTax Online return? see: https://ttlc.intuit.com/replies/6602873