You are only eligible for head of household if you have paid over one-half the cost to maintain your household And you a qualifying person as a dependent.
If you entered Single and did not enter a dependent you cannot have head of household filing status.
See this TurboTax support FAQ for head of household - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-filing-status/qualify-head-household...
