Preheat oven 350F, with racks in upper lower thirds. Whisk together flour, baking powder, and salt. In a large bowl, using and electric mixture, beat butter, granulated sugar, 1 tablespoon orange zest, and 2 teaspoon lemon zest 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, 12-15 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 1 tbs orange zest, 2 tsp lemon zest, citrus juices, and confectioners' sugar until smooth. With a small spoon, spread glaze over each cookie. Let set for 1 hour.