This will depend on if you're using an Android or an iOS device. How to Sync contacts on an Android: You can always turn on continuous contact loading on your messenger account on your mobile device. Otherwise, from your home app tap on your photo in the upper right hand of your screen. Tap on people. Now tap on sync contacts. You can use this same method to tun on or off the syncing of your contacts on your phone. For iOS devices: On an iOS device, the image will be at the top left of your screen. This is the only difference. You'll tap on the image, Tap on People. Now tap on sync contacts. You have the same options to turn on or off the syncing of your contacts.