Little red light on iphone?

I'm in the dark right now on my iphone, and there's a little red light just above the speaker on my phone (it's a 6) and i tried looking it up but it says that it's the "water detection sticker" or something, but my phone has no water damage, and hasn't been exposed to any water. So what is this light really?

Touch ID not working for App Store

So my Touch ID is not working. I have it set up. I went to my settings and turned it on for my App Store. But when I turns on, it stays for a second and glitches. The toggle moves on its own and turns it off and back on. Then it says "There was a problem setting up biometric authenticifcation on this device. Try again later." Then, when I turn it off to try again, it glitches and turns it on and back off. Has anyone else been getting this? What else can I do. If the model matters, it's an iPhone 6s Plus.

Iphone touchID for app store?

Every time i try to set up my touchID for the app store it won't let me and it just says there was a problem setting up biometric authentication. I just don't want to type in my password every time i download an app. Any help?