Open the Facebook app or website
Go to your profile
Tap the three dots menu next to Edit Profile
Select Lock Profile
Tap Lock Your Profile to confirm
If you do not see Lock Profile
Go to Settings and Privacy
Open Settings
Check Privacy settings and profile visibility options
Use audience controls to limit who can see your posts, photos, and profile details
You can also:
Set future posts to Friends only
Limit past posts
Review tags before they appear on your profile
Hide your friends list from public view
Restrict who can send you friend requests or message you