i need help with allowing camera access to instagram snapchat and messenger

i read a reply saying to go to preferences in settings but my iphone is updated and doesn’t have “preferences” anymore so i read another reply and it said to delete the app and when it asks for access to the camera to click “allow” but i logged back in to snapchat and it said the same thing as before to open settings but nothing showed up to access anything! please help me if you can i’m in a rush to do this!