From your Mobile Device:
Open the Facebook App
Tap menu at the top right corner for Android users, or at the bottom right for iPhone users
Tap the gear icon at the top right next to the magnifying glass
Tap “See more in Accounts Center”
Tap “Connected experiences”
“Sharing across profiles” allows you to control if you want to share from your Facebook account to your Instagram account or vice versa
Tap the Profile you would like to share from
Toggle the radio button on to automatically share your story or post
From your Computer:
Go to www.Facebook.com and log into your account
Click on your photo at the top right of Facebook
Next, click on “Settings and Privacy”
Then, click on “Settings”
Click “See more in Accounts Center”
Click “Connected experiences”
“Sharing across profiles” allows you to control if you want to share from your Facebook account to your Instagram account or vice versa
Click the Profile you would like to share from
Toggle the radio button on to automatically share your story or post