Animation replays in reverse

I am trying to add an animation for a robotic arm. Every time I add an animation for the arm to move to a certain point and play it, the animation I added plays and it automatically plays the reverse of the animation as well. The attached video shows the robotic arm. It shows me trying to change the angles of the robot's link to 45 degrees in animation but the link goes back to its initial position at the end. Please can someone tell me what I am getting wrong?