US Army Regulation DA PAM 670-1 (para 4-10b(2)).

(2) Wear. The beret is worn so that the headband (edge binding) is straight across the forehead, 1 inch above the eyebrows. The flash is positioned over the left eye, and the excess materials is draped over to the right ear, extending to at least the top of the ear, and no lower than the middle of the ear. Personnel will cut off the ends of the adjusting ribbon and secure the ribbon knot inside the edge binding at the back of the beret. When worn properly, the beret is formed to the shape of the head; therefore, Soldiers may not wear hairstyles that cause distortion of the intended shape of the beret. Figure 4–3 shows wear of the beret. The beret is equipped with a stiffener on the left front for attaching organizational flashes and insignia.

US Air Force Regulation AFI 36-2903, Chapter 6, paragraph 6.2.5.1.

6.2.5.1. Position the beret headband straight across the forehead, 1 inch above the eyebrows. Drape the top over the right ear and the stiffener. Align cloth flash above the left eye. Adjust ribbon for comfort, tie in a knot, and tuck inside or cut-off. The cloth flash will be sewn to the center of the stiffener, with hook and loop backing for ease of change out for cleanliness of the flash, 1⁄4 inch above and parallel to the headband.