How do I print a different address on each label in Avery Design & Print Online?

Find the Sheet Navigator located in the upper right of the screen. Click the tab to switch from Edit All to Edit One. Then, click on each label in the Sheet Navigator to show that particular label in the center of the screen, and enter the address. You can use Edit All to set the formatting for the entire sheet (such as design backgrounds), then switch to Edit One to make individual changes.