Outlook 365 - To Do bar show wrong calendar

I have configured two email accounts:

- #1 with my provider - this is my main account for mail and calendar

- #2 with Hotmail - secondary account when I don't want to use my main account

I have the "To Do" bar visible for calendar and tasks. Tasks are shown for the #1 account, no issue. However, calendar is shown for #2 account which I don't use the Hotmail calendar.

How can I change that to #1 account calendar which I use for all my appointments? 

Attached screen shot in case that helps.