Why do my tax amount I owe not go down when I put in charitable donations?

[JulieCo]

It depends.  For 2018, the standard deduction amounts increased significantly.  Charitable donations are itemized deductions and, in order for itemized deductions to be reflected on your tax return, the total itemized allowed needs to be more than the standard deduction.  The standard deduction amounts for 2018 are $12,000 single/MFS, $18,000 head of household, and $24,000 for a joint return, with additional amounts for over 65 and/or blind. 

Once income is entered into TurboTax, the standard deduction amount is recorded on the return.  As itemized deductions are entered, there will not be any impact on the return until the total itemized is more than the standard amount.  This is more then likely why you are not seeing any change in the amount due as you have entered charitable donations.