I'm living with my folks and helping with groceries. I believe I've determined that since I cannot access the form that inquired about my rental situation, I need to find form 1040-X. How do I do this?
If you have not filed a tax return yet, you do not need to click on anything that says "Amend." You only use a Form 1040X if you have already e-filed a tax return and the IRS processed the return with your mistakes on it.
You simply need to make some changes to the tax return you are still preparing. That does not require a 1040X.
There is no place to enter anything about rent on a federal return so it sounds like you made a mistake on a state return, since some states have credits for rent or heat. You need to go back to the entry screen where you said you paid rent, and delete the answer. You did not pay rent. You are merely participating in family cost sharing, which is not entered on a tax return.
If you tell us what state you are in someone may be able to help further with how you need to navigate the state form.