Have to enter iTunes password any time I open an app that was downloaded from iTunes store

This just started...Any time I open an app that I downloaded from the App Store on my iPhone or iPad, I get a popup that asks me to enter my iTunes password. I searched fixes and tried to restart the device, tried signing out of and back into iCloud, and even changed the password for my Apple ID. Nothing worked. Any suggestions? Been having problems with syncing the devices with my iMac also. I am thinking about going back to Sierra and iOS 10!!!