If multiple Identities are configured within Outlook 2011, the follow article will instruct you on how to switch between them. 

1. To switch Identities within Outlook 2011, simply hold down the Option key when launching Outlook.  This will launch the Database Utility. 

2. Select + "Create a New Identity", then "Set as default".

Please note the following: 

1. You can no longer select Switch Identities in Outlook as this former Entourage feature is no longer available.

2. If several users wish to use Outlook on the same computer, the recommended procedure is to create individual user accounts and run instances of Outlook in each account. This method is much more secure than using separate identities, since your Outlook data is now protected more effectively inside the user account by Mac OS X itself.

3. If Identities are switched on a frequent basis, it is recommended that the Database Utility remain open while Outlook is open. However, Outlook must always be closed in order to switch identities.