1099-Q Earnings being taxed for full time student dependent but he had GI Bill for tuition, money was used for room and board

Q. Why are the 1099-Q earnings being taxed for me?

A. You need to enter the offsetting room and board expenses.

But better yet, just delete the 1099-Q. 

You can just not report the 1099-Q, at all, if your student-beneficiary has sufficient educational expenses, including room & board (even if he lives at home) to cover the distribution. When the box 1 amount on form 1099-Q is fully covered by expenses, TurboTax will enter nothing about the 1099-Q on the actual tax forms. But, it will prepare a 1099-Q worksheet for your records. You would still have to do the math to see if there were enough expenses left over for you to claim the tuition credit. You also cannot count expenses that were paid by tax free scholarships. You cannot double dip! 

References:

1. On form 1099-Q, instructions to the recipient reads: "Nontaxable distributions from CESAs and QTPs are not required to be reported on your income tax return. You must determine the taxability of any distribution." 
2. IRS Pub 970 states: “Generally, distributions are tax free if they aren't more than the beneficiary's AQEE for the year. Don't report tax-free distributions (including qualifying rollovers) on your tax return”.

Be advised that you may use 529 money for home living expenses ("room & board") but you are limited to the lesser of your actual costs or the school’s R&B “allowance for cost of attendance” for student living with parents. The school should be able to provide you with that number.