Hello,
For Example : We have created a new user named : symantec in AD. We want to make this account as the Backup Exec Service Account.
1 : Before going further, first change the account as it was before.
(So we will be able to open the console of Backup Exec), go to services window stop all the BE Services and change it to the original account.Only remote agent service and the SQL service must run on Local system
2 : Open Backup Exec, add the newly created account (symantec in our example) and uncheck the check box "Restricted account" nad check the box Default account.
3 : Highlight the new account and click on System Account
4 : go to tools-->Backup Exec Services and Restart all Services
Make sure to add the new account in the Local Admin Group of the Backup Exec server if its not a Domain controller.
Please let me know if you face any issues