Specifically for Instagram, you can go to the app in the App Store and sort the reviews by most recent. There are many people that are experiencing the app crashing using many different devices. This specific problem will need to be fixed by the developer. You will also notice that they have updated the app 10 times in the last month attempting to resolve issues that users have experienced. You may just need to be patient with this specific app developer before they can get it right. They do have a support page here, but contacting them directly may be more difficult.
https://help.instagram.com