The jam squares are located at the corners. However, they are under the six-layered ice cubes. Despite this, though, one of the layers will automatically be removed on all four ice cubes due to how the initial candies are formed and the board flow pushing them against the ice cubes.
The color bomb in the center seldom works since it is also under an ice cube and must be activated by a striped candy.
Clear the ice cubes at the corners to expose the jam spaces.