Mix apples and pineapple tidbits in buttered crock pot. To the reserved pineapple juice, add orange marmalade, maple syrup, apple cider and curry powder. Stir and pour over apple mixture. Cover and cook on HIGH for 1 hour.
To make Topping: Combine flour, oats, brown sugar and cinnamon in bowl. Cut in butter until mixture is crumbly. Spread topping over apples. Cook on LOW 2 1/2 to 3 hours until done. Let cool 10 minutes before serving.