Military retirement pay is subject to federal income tax. Some states do not charge income tax on military retirement pay, as each state has their own income tax laws. Therefore, you would need to check with your state to see their requirements.
See more from the IRS here:
If your retirement pay is based on age or length of service, it’s taxable and must be included in your income as a pension on lines 4a and 4b of Form 1040. Don’t include in your income the amount of any reduction in retirement or retainer pay to provide a survivor annuity for your spouse or children under the Retired Serviceman's Family Protection Plan or the Survivor Benefit Plan. https://www.irs.gov/publications/p525#en_US_2018_publink1000229269
Regarding changing from to the standard deduction, when any income is entered into TurboTax, the standard deduction gets input on the return. The only time the standard deduction will be recommended to be changed is when your itemized deductions are MORE than the standard deduction amount.
Below is more information, plus steps to be brought to the section where you can switch your return from the itemized deduction to standard:
https://ttlc.intuit.com/replies/3300919
