How to update w4 to get a bigger paycheck?

I want to update my w4 to get a bigger paycheck, what should I input for Line 3 or Line 4? I used the IRS Estimator tool and it's telling me to put $4,834 for Line 3. Does anyone know how they came up with that calculation? I understand that Line 4 you are able to specify if you want to withhold MORE taxes which doesn't apply to me.

Expected tax withholding $3,698

Anticipated tax obligation* $1,913

Projected refund $1,785