previously, I was using an older version of iOS on my 7+, then about a week ago I finally decided to upgrade it to the latest version. Now, when a YouTube video plays, it plays on their website, through Safari, not their app that is installed, and there's a black button near the top to open app, and so I've done that, but it doesn't open the app, it opens the app store and offers to get it, even though I already have it. It acts like it doesn't know the app is already installed. I've tried deleting it and re-downloading it, that didn't help. Help!