Go to your profile and use activity log menu below your cover photo.
Anyone who can see a certain post will also see likes and comments on the post.
The person who posts has control over the audience who can see it. Every post includes an icon that lets you see the audience. Audience choices include Friends, Public and more choices can be set.
Remember, Someone can change the audience of the post at any time and you won’t be notified.
A friends who share photos with their friends only can later update the audience to Public.
Any comment made by you intended for friends can become public then. Don't get into trouble by bad commenting your principal or class teacher