Exchange ActiveSync setup

Hello all,
I work at an IT department for an offshore drilling company, we have it configured so that when a user first opens his Outlook through Citrix XenApp, it should autofill his email and not require any manual input. The issue is that we migrated the exchange server, and the Outlook now defaults to the wrong profile, causing help desk to have to create a new profile which will create as it should. How do I change the settings and where do I configure this?