Appstore keeps forcing me to enter password now?

I used to be able to get a new app with my fingerprint but in January my iphone like signed me out of my appleID completely and ever since I've been forced to re-enter my extremely long nonsense password in order to add anything from the appstore every time now which functionally means I just can't do anything on the appstore because I have to hunt down the secret post it note and try to decipher my handwriting within the number of attempts allowed. Any idea as to why it stopped accepting my fingerprint or ideas on how to switch it back to fingerprint?