I've now set up 4 email accounts with respective inboxes in Outlook.

On my other computer, Outlook was set up to show all incoming email from all 4 accounts with a single click on a "universal Inbox" in "Favorites". Thus I could see all my most recent messages regardless of which account they came from.

How do I make this "universal Inbox" in "Favorites" to show all incoming email from all 4 accounts with a single click?