Where is my refund for 2018?

Do you mean you filed the 2018 return last year?  If your refund was sent to a closed bank account, the bank would send it back to the IRS, and then the IRS would mail a check to the address you put on your tax return.  But you say you moved.  You have not given us any sort of timeline for when you filed, closed the bank account, moved, etc. so it is difficult to advise you.

First--do you even know if your 2018 return was accepted?  What does it say in your TurboTax account?  Does it say "accepted," "rejected", "Printed," or "ready to mail?"  If it says anything other than accepted, then the IRS did not even get the return.

  Either it was rejected and you did not notice and/or follow up, or it was never filed at all.

If you chose to file by mail, you had to mail it yourself.  TurboTax does not mail it for you. 

If it was not filed, then print, sign and mail it now.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

If the return was accepted--did you track it during the time period when you could have tracked a 2018 tax return on the IRS refund site?  You cannot track a 2018 refund now--it only shows 2019 refunds.  

Did you choose to have your TurboTax fees deducted from your federal refund?

Your tax refund was not sent to TurboTax.   TurboTax does not handle your refund at all.

Santa Barbara Tax Products Group, LLC  (SBTPG) is the bank that handles the Refund Processing Service when you choose to have your TurboTax fees deducted from your refund. This option also has an additional charge from the bank that processes the transaction. 

You can contact them SBTPG, toll-free, at 1-877-908-7228 or go to their secure website www.sbtpg.com 

https://ttlc.intuit.com/questions/2580357-who-provides-the-refund-processing-service 

If it was filed and accepted, then you have to follow up with the IRS to see what happened.   TurboTax cannot find out about it for you.

https://ttlc.intuit.com/community/refunds/help/how-do-i-replace-a-lost-or-damaged-tax-refund-check/00/26320