Bells can be moved with two-finger gestures over the box containing the bells.
To control one bell, or move two bells in the same direction, simply swipe with two fingers in the directions indicated by the arrow buttons: left to move down, down to stay in place, right to move up, or up to undo.
If you have two bells, they can be moved in opposite directions by a pinch (bring bells toward each other) or spread (move bells apart). Either motion should be done horizontally. To move one bell while the other makes a place, hold one finger mostly still while moving the other horizontally. The left-most finger corresponds to the bell in the lower place at the time that you make the gesture.
If you have two bells, they can only be controlled by gesture if they are in the same row, and if the gesture you have made is valid for *both* bells. Along these lines, the two-finger swipe up will undo the last move of both bells.