On the task that is called Chocolate River Challenge I cannot figure out..

First, make sure Patrick's pick up and throw ability is upgraded. Get rid of the bad guys, then head towards the room that looks down on the area where you started the level (opposite the room where Patrick swings over the tub of chocolate). Hit the boxes you see, making sure at least 1 is left. Grab a box and head towards the 4 buttons which open up the Challenge. Stand near the wall (closest to the buttons) and throw the box as if you were throwing it very far (use the upgrade). If you aim right, you'll hit all the buttons at once. The task itself is pretty self explanatory. Avoid the spikes that run through each section of the river and jump on the marshmallows to get to the other side. That's it. Good luck!