How do I change the Unit Description in my address?

Where exactly does TurboTax ask for a unit number? In the mailing address in the My Info section there is a space for Apt. #, but you can leave it blank. I'm not aware of any place in the federal section where it would ask for a unit number, or any reason that it would matter whether you live in a house or an apartment. Is that question coming up in the state section? If so, what state is it, and what topic in the state section is it in?

According to the USPS these all have the same characteristics:  Unit, Apt, Suite.  These are all interchangeable.  Enter your Unit # in the APT# box.  Others have entered their Suite # in the APT# box... others have entered their APT#.  All are acceptable and will not reject your form.