Apple won't store my iCloud password. Does Apple not trust their own KeyChain? Make it long, make it complex, Apple will even suggest really good passwords ... but for iCloud I have to remember that really long, really complex password because Apple says "uh, uh" ... AND you can't paste in the password! Nope, got to remember the super secure password.
Oh, but it gets better. Now I have to draw each character on my watch! The WatchOS is really helpful ... "Nope, wrong password, dumb dumb, you can't pass a 1st grade penmanship class". Is there a GUIDE to drawing 1st grade letters so I can be clear if it is a capital O, a lower case o, or a zero? Yep, use long, complex password but avoid anything that looks like an O, or any other gatchas that Apple isn't going to tell me about, just "you failed".
