To change iPhone's avatar to Memoji, follow the below-mentioned steps.  Step 1: Open your iPhone setting from the home screen and scroll down to the “Messages” tab. Step 2: Tap on “Share name and Photo” in the messages tab. Step 3: Select “Choose name and photo” from the bottom in the “Share name and photo” tab. Step 4: Add Memoji as your Apple id picture by clicking on the “Add picture” icon. Step 5: Hit on “Done” to save the changes.