Where do I enter college student living expenses? Does it go in the Books and materials not required to be purchased from the school?

There is nowhere to enter the college student's living expenses because they are not an allowable expense for any Education Credits.

However, if your child received a scholarship that does not stipulate how to use the funds, you may allocate the scholarship to the room and board expenses. 

Q. Where do I enter college student living expenses?

A.  You don't enter them at all. They are not qualified expenses for a tuition credit.

The exception is if you had a distribution for a Qualified Tuition Plan (529 or ESA).  Room and board, even off campus,  are qualified expenses for a QTP distribution. 

As RaifH said, if you student had scholarship, you can (usually) shift the scholarship money to room and board, so that you can claim the tuition paid for the tuition credit*.  In the TT interview, you will be asked if any of the scholarships were used for room and board. Answer yes, then enter the amount needed to claim the credit (usually $4000).  Scholarships used for tuition, fees, books and required computers are tax free.  But once you shift the money to R&B, that amount becomes taxable income to the student (not the parent). 

*There is a tax “loop hole” available. The student reports all his scholarship, up to the amount needed to claim the American Opportunity Credit (AOC), as income on his return. That way, the parents  (or himself, if he is not a dependent) can claim the tuition credit on their return. They can do this because that much tuition was no longer paid by "tax free" scholarship.  You cannot do this if the school’s billing statement specifically shows the scholarships being applied to tuition or if the conditions of the grant are that it be used to pay for qualified expenses.

Using an example: Student has $10,000 in box 5 of the 1098-T and $8000 in box 1. At first glance he/she has $2000 of taxable income and nobody can claim the American opportunity credit. But if she reports $6000 as income on her return, the parents can claim $4000 of qualified expenses on their return.

Books and computers are also qualifying expenses for the AOC. So, extending the example, the student had another $1000 in expenses for those course materials, paid out of pocket, she would only need to report $5000 of taxable scholarship income, instead of $6000.

Another way: say the scholarship paid for room & board, in the parent’s interview.

This is not some sinister scheme. From the 2019 form 1040 instructions (pg 95): “You may be able to increase an education credit if the student chooses to include all or part of a Pell grant or certain other scholarships or fellowships in income. For more information, see Pub. 970, the instructions for Form 1040, line 18c, and IRS.gov/EdCredit.  Page 16 of PUB 970 (2019) actually has examples of how to do the “loop hole”.  https://www.irs.gov/pub/irs-utl/Pell%20AOTC%204%20pager.pdf