I would like to know why my total credits from last year to this year are $1953 difference? My child is not over 17 he is 17.

If your available Child Tax Credit is greater than your tax liability, the Child Tax Credit can only reduce your tax bill to zero — you don’t get any unused portion of the credit back as a refund. However, you may be able to claim the Additional Child Tax Credit

To claim the Additional Child Tax Credit you must have a minimum of $2,500 of earned income to claim the ACTC. Earned income can come from salaries and wages, self-employment, and some disability payments. 

Form 8812 is used to calculate your Additional Child Tax Credit. TurboTax will ask you a few simple questions about your dependents and income, calculate your credit, and fill in all of the right forms for you.

The credit will be reported on form 1040 line 28. 

What is the Additional Child Tax Credit?

the child tax credit is limited to children UNDER the age of 17 - so I suspect most of the $1953 difference is due to losing the child tax credit ( up to  $2000) and replacing it with the Other Dependent Credit (up to $500)