I'm filing single HOH. With no LTC prems or expns on my fed return why does TT keep error back to the Medical Expenses Worksheet to add a DOB for spouse to calculate LTC?

Did you use an account where you did file a joint return in the past ?   If so then you must have some remnants of the spouse on the return ... either scour the account to remove them ...  OR   start over in a new account.