Downloading apps

I've used the touch feature on my Iphone 7plus to download apps from the Apple Store for a couple of years now. After the most recent IOS upgrade, it's stopped recognizing it. I place my thumb and it rings that it's a match, then a screen pops up that states Verification Required. Tap Continue and sign in to view billing information. It is only asking for my password, I enter that and it locks me out saying I must sign in to view billing information. It's a cluster. It won't let me sign in. I try putting my password in a few times then it asks me to change my password! Help! Pretty please :)