Proper wear of Service Stars (source: BSA card 34226A): Service stars may be worn by all youth and adult members who have at least one year of tenure with the BSA. The stars are worn with the appropriate color background for the phase of Scouting in which the service was rendered.
Gold backs - Cub Scout service
Green backs - Boy Scout service
Brown backs - Varsity Scout service
Red backs - Venturing service
Blue backs - Scouter service
If an individual's primary registration is in one phase of Scouting and later in another, separate stars with the appropriate background and numerals may be worn simultaneously. Or, leaders may combine youth and adult tenure into one or two stars with blue background. Only one is worn at a time 3/8" above, and centered, over the left pocket. If a medal or embroidered emblem knot is worn, service stars are worn 3/8" above the medal or knot.