Grasp the back of the battery pack at the bottom base of the hand grip. Push in on the small indented release lever and slide the Ryobi battery off.
Hold the Ryobi's chuck collar tightly with one hand. It is located between the chuck lock and the spinning rotation selector.
Twist the chuck lock counterclockwise, or left, firmly until the chuck collar loosens its grip on the drill bit.
Pull the old drill bit out and slide the new one in.
Grasp the chuck collar again with one hand. Twist the chuck lock to the right tightly until the new drill bit is tight.
Replace the slide-on battery pack and squeeze the trigger once or twice just to make sure it looks as if the new bit is clearly centered.