The force of the girl pushing down on the bench is the equal and opposite to the force of the bench pushing up on the girl. Therefore, they are balanced forces and the girl does not move vertically.
The force of the bottom strawberry-flavored scoop of ice-cream pushes up to the cotton candy-flavored ice-cream above it and the cotton candy-flavored ice-cream pushes down onto the bottom strawberry-flavored ice-cream scoop. Since both of the forces are equal and opposite to each other, they are balanced forces and the scoops of ice-cream do not move.
Ugh... So heavy... I can't carry it any longer...
Since the force of the boat is greater than the force of the current pushing back on it, the boat is able to move forward. The forces are not equal; therefore, they are unbalanced.
The force of the boy is much more larger than the force of the girl. This will eventually cause the girl to fall down and lose the tug of war. Since the forces are not equal, they are unbalanced. The rope will move toward the boy during the whole process because his force is larger.
The force of the box pushing down is greater than the force of her arms pushing up to try and hold the heavy box. So, her arms fall down and so does she. This demonstrates unbalanced forces because the force of the box and her hands are not equal. The change in motion occurs when her arms fall down because there is a change in direction.