If you have an iPhone, follow these instructions:

1. Tap your ‘Settings’ button
2. Scroll down and click on ‘Facebook’
3. Click ‘Settings’
4. Click ‘Auto-Play’
5. Then choose ‘Wi-Fi only’ of ‘Off’

If you have an Android, follow these instructions:

1. Open your Facebook app
2. Go to ‘Account Settings’
3. Click ‘App settings’
4. Then choose ‘Auto-play only on Wi-Fi’ or ‘Off’