apple id sign-in
I am being constantly asked to sign-in to my apple id. This happens on my iPad, my iPhone, my apple tv, and my iMac. For sometime I would go through the whole process of signing in, and often the result would be that I was informed my account was locked which then entailed the laborious process of unlocking it. Lately I have just been selecting 'not now', or 'cancel' instead, even though the message will often keep popping up multiple times. Eventually it will disappear and I will be finally able to use my device. How do I fix this? Thanks
iMac 21.5″, macOS 10.13