How do I get Turbo Tax to change my filing from single to head of household?

Are you eligible for Head of Household - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-filing-status/qualify-head-household-2021/L0NxUtVc2_US_en_US?uid=m646001n

On the right panel in TurboTax, under 2024 Taxes, choose My Info, Edit, click until you get to the screen About your household.  Make sure you have entered your dependents. Continue on and answer that you paid more than half the cost of to keep up your home, if you did so. This will allow you to file Head of Household.

Here is some more information about qualifying for Head of Household status: Guide to Filing Taxes as Head of Household