As NASA employees, they did not retain their military titles (NASA is a civilian agency, though obviously it has strong ties to the military). Armstrong worked as a professor at Cincinnati and as a spokesman for many companies. He also served onNASA accident boards and on the board of several companies. Collins worked briefly in PR for the State Department and was director of the National Air and Space Museum, then undersecretary of the Smithsonian, then in aerospace. Buzz Aldrin worked briefly as commandant of Edwards AFB then retired from active duty; he struggled with alcoholism and depression.

I should maybe also mention that only Aldrin and Collins were Air Force pilots. Armstrong was a naval aviator.

Neil Armstrong retired from the NASA program pretty quickly and then became a professor at Purdue. In addition to being an outstanding pilot, he seems to have been an intellectual at heart and seems to have enjoyed his work. He died a few years ago as you probably know. I dont believe they were in a branch of the armed forces when they were in NASA.