In a small bowl, combine pretzels and 3 teaspoons of sugar;stir in butter. Press into an ungreased 13x9 inch baking dish. Bake at 350°F for 10 minutes. Cool on a wire rack.
In a large bowl, dissolve gelatin in boiling water. Add pineapple and oranges. Chill until partially set, about 30 minutes.
In a small mixing bowl, beat cream cheese and remaining sugar until smooth. Fold in whipped topping. Spread over crust. Gently spoon gelatin mixture over cream cheese layer. Cover and refrigerate for 2-4 hours or until firm.
Cut into squares. Garnish with additional whipped topping if desired.