just a sincere question: Why would you give Yahoo access to your daily schedule and all your appointments, notes, memos and to do lists? That's a lot of privacy to give up for a company to exploit.

I have several Yahoo email addies, but only use what is absolutely necessary on their site to send my emails.

That is the purple layout that was rolled out a few months ago. If so an update yesterday moved the calendar button to the top left above "Compose" and below the Yahoo Mail logo. Calendar is the third icon over with the "31" representing a calendar date.

https://overview.mail.yahoo.com/features/folders