You are correct that it says subtract line 74 from line 63, but the other number that impacts that amount is actually line 79, tax penalty. $6096-$3673=$2396. Does the amount on line 79 equal $75?
Normally that amount is for underpayment of taxes, which it looks like you are overpaid. However, there are other reasons for penalty. Also, if you chose to annualize your income, that could cause this.
Let me know if this resolves your question or more details based on this info.
