Preheat oven to 350 degrees, with racks in upper and lower thirds. Whisk together flour, baking powder, and salt. In a bowl of an electric mixer fitted with the paddle attachment, combine butter, granulated sugar, 1 tablespoon orange zest, and 2 teaspoons lemon zest and beat on medium-high until pale and fluffy, 3 minutes, scraping down bowl as needed. Beat in eggs, one at a time. Add flour mixture; beat to combine.

Roll dough into 1-inch balls and place, 2 inches apart, on parchment-lined baking sheets. Bake until edges are lightly golden, 12 to 15 minutes, rotating sheets halfway through. Let cool on sheets on wire racks 5 minutes, then transfer cookies to racks and let cool completely.

Whisk together remaining tablespoon orange zest and 2 teaspoons lemon zest, citrus juices, and confectioners' sugar until smooth. Dip the top of each cookie in glaze to coat. Let set 1 hour.