For the crust, mix the pretzels, butter and 3 TBL sugar. Press into 9 x 13 pan and bake for 7 minutes. Set aside and let it cool.
In a mixing bowl, beat together the cream cheese and 3/4 cup sugar. Fold in the whipped topping, and spread over the cooled crust. Refrigerate till well chilled.
In a mixing bowl dissolve the gelatin in the boiling water, and allow to cool slightly. Add the strawberries and pineapple and pour over the cream cheese mixture. Refrigerate till serving time.