How to enable iCloud Notes on my Mac? In Internet Accounts, I see my iCloud account alright, but under it, "Notes" is not checked, and I cannot change that (the whole UI element is disabled):



I tried re-entering iCloud password several times, but I don't see a way to make these settings editable. Also went to icloud.com but didn't see an option for this there either. Any ideas?

OS X Yosemite (10.10.5)
The problem is not enabling notes, the problem is that your icloud account is frozen until you validate it. If that prompt does not work, try signing in at https://appleid.apple.com or https://icloud.com and do it from there.