icloud demands constant password

Since two or three days a message from icloud jumps telling me I need to enter my password in order to continue using icloud on my computer (window 10). I installed nothing new on my computer, I made no changes at all. I did change a week or so ago the need for verification, instead of one I made two, but now I deleted the second option.

I have tried signing out and signing in again, I updated icloud, rebooted the computer. I canceled the need for two verifications, I had to change my security questions which I did. I signed out and in again but this announcement keeps coming back and driving me nuts.

Please help.