Did my taxes, the HR block tax agent said that next year I will owe unless I adjust my withholdings on mypay…

I’m a active duty military member the tax agent told me I will owe next year unless I adjust my withholdings on MyPay, that being said I went to MyPay to see and it states my withholdings is at $0. I don wanna owe next year so I wanna get this situated asap. Has anyone experienced this situation before?