Belly button piercings are popular mainly amongst teen females, but people of all ages and genders can get them. The most common type of jewelry used for belly button piercings are barbells which are often called "belly bars" when used in this particular piercing. Changing the jewelry can be tricky at first, but with a little practice you can do it in under a minute.
Wash hands with warm water and antibacterial soap. You want everything to be clean to ensure that no dirt will get inside the piercing. Dry hands with a towel.
Wash the new piece of jewelry with a saline solution. Set it aside in a clean spot and let it air dry. It should be dry around the same time you get the jewelry out of your belly button.
Grab each end of the barbell. Once you have a firm grip, turn the bottom ball to the left until it starts to unscrew. Screw the ball completely off and set it aside. Slowly pull the jewelry out of your belly button. Be gentle because the threads on the barbell could cut the inside of the piercing.
Take the new barbell and unscrew the ball on either end. Once the ball is removed, carefully line the jewelry up with your piercing. Slowly slide the jewelry through the entire hole. Do not force it through, as this could damage the piercing.
Screw the ball back on once the jewelry is in place. Make sure it is tight enough that it will not come unscrewed on its own.