Hi Alaa,
Generally speaking, we do not need to reconfigure Outlook profiles or change any settings on clients after changing the CNAME and MX record to point to Office 365. However sometimes users may experience connectivity issues after deployed the hybrid environment, in this case creating the new Outlook profile is always the first step to solve the issue.
Regarding BlackBerry devices, if you are using the BES or BBCS (BlackBerry Business Cloud Services) configuration, Research in Motion (RIM) is best suited to help you with Office 365 BlackBerry Business Cloud Service issues and can give you additional information and support at the following sites: http://supportforums.blackberry.com/
Best Regards,
Bourne Zhang