syncing two accounts

emmanuel.j

I created another user account because of unsatisfactory username. Now I am unable to sync the previous library into my new library.

dstillman

You're probably going to have to provide more details on what exactly you're doing and what isn't working, but, generally speaking:

First make a backup of your Zotero data directory. Then sync with the old username/password, make sure the data is correct on zotero.org, enter the new username/password into the Sync pane of the Zotero preferences, sync. Zotero will warn you that you're changing usernames.

Beyond that, see Reporting Bugs.