Can you look at my 2017 and 2018 tax returns and tell me where I paid less tax and what caused the refund to be so different?

Sorry nobody can do that for you.  You have to compare them yourself.  For one thing, they reduced the withholding tables so you got more back in your paychecks each month.  There was a lot of new tax changes for 2018.

Do you Itemize Deductions?  Big changes in that.  FAQ on 2018 changes <a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return">https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return</a>

For 2018 the standard deduction amounts are:
Single 12,000 + 1,600 for 65 and over or blind
HOH 18,000 + 1,600 for 65 and over or blind
Joint 24,000+ 1,300 for each 65 and over or blind
Married filing Separate 12,000 + 1,300 for 65 and over or blind

The most common reasons people with income and expenses that are similar from 2017 to 2018 have refunds that are a lot different this year are:

1. With the lower tax rates, less was withheld from your wages.  Compare box 2 of your W2 from last year to this year or line 17 on your 1040 this year to taxes withheld on your 1040 form from last year (the line will depend on your form)
2. Itemized deductions are less due to changes in the law limiting the deduction for state and local taxes to $10,000 and the elimination of Employee business expenses and other miscellaneous expenses
3. Elimination of Personal Exemptions.  Generally, a single person or married couple with no kids that did not itemize is making out better here, but others are not. 
4. You have kids and one of them turned 17.  This would make them ineligible for the child tax credit and only give you the $500 Other Dependent Credit for your child.

Overall, everyone has a different situation.  The best way to figure out why your refund is different this year is to look at your 1040 for last year and compare it to this year.  You will need to look at the words on the line and the schedules as the forms have totally changed this year. 

thank you

Legally, we cannot review your returns. However, for an extra fee, with TurboTax Live a tax expert can review your return and answer any specific questions you may have.

https://ttlc.intuit.com/replies/6071042

thank you