If you have not already filed and submitted your tax return follow the steps below:

1. Sign into your account, click take me to my return

2. Click the File heading

3. Follow the prompts for Step 1. When you get to Step 2, this is where the bank account information will be. Follow the prompts to edit your bank account information.  

If you have already filed and submitted your tax return you are unable to edit the bank account information once the return has been accepted. If your return has been filed and submitted and rejected then you are able to change the information, just follow the steps above. 

If the IRS is unable to deposit your refund into your account, they will mail you a refund check. 

There is a great FAQ that explains this further: https://ttlc.intuit.com/replies/3302459