Crush the pretzels, then mix with the butter and 1/4 cup of the sugar. Press into a greased 9x13 pan. Bake at 350 for 10 minutes, then let cool completely.
Mix the blue jello with one cup of the boiling water, stir. Add 3/4 cup of the cold water and stir. Add the blueberries and set in fridge until ready to use.
Repeat step 2, but with the strawberry jello, and sliced strawberries. Leave on counter until ready to use.
Beat the cream cheese with the remaining 1/4 cup sugar. Slowly add the milk and fold in the cool whip. Spread about 1/3 of the cream cheese mixture over the pretzel crust, gently so you don't break up the crust too much. Pour the blue jello mixture over the cream cheese layer. Let sit in fridge until set. Then spread the remaining cream cheese over the blue jello. Carefully pour the red jello over top. Set in fridge until firmed up, and ready to serve.