Please follow this instruction:
On your TurboTax Online return, go to the left side and click on "My info"
On "My info", you will see a list of options. Go down and click on "Contact information"
You will find your mailing address information. You can edit your Street Address, City, Province, and new Postal Code.
Once you finish updating, click on "Continue" to save your changes.
By pressing “Summary” on the left side of your TurboTax Online return, you will be able to view the changes made.
If you are still not able to update your mailing address, you can contact our support team and share the screen with them for the best help.
Here is the link for you to contact the support team: Contact Us
If you require further assistance please contact our phone support team or contact us directly on Facebook or Twitter.
Thank you for using a TurboTax.