Instagram allows everybody to see my posts by default, how can I let only approved followers see them?
Anybody can view your Instagram posts by default, but you can make your account private so that only people you approve can follow you and see your posted photos and videos. You can't change this setting from a desktop, so you'll have to do it in the app on your iPhone. Launch the app and tap on the profile icon in the bottom right. Then tap on the gear icon to the right of "Edit Profile" and scroll down until you see "Private Account." Toggle it on.