How do I update this status within TurboTax Online? You don't and you can't ... TT never gets any updates from the IRS when you mail in a return. This is just like if you walk out of a tax preparer's office with a paper copy in your hand ... that paper copy will never be updated.
Once your federal return has been accepted by the IRS, only the IRS has any control. TurboTax does not receive any updates from the IRS. Your ONLY source of information about your refund now is the IRS.
You need your filing status, your Social Security number and the exact amount (line 20 of your Form 1040) of your federal refund to track your Federal refund:
https://www.irs.gov/refunds
