The ARIS Agent user has access to ARIS Cloud Controller (ACC). If you did not change the default password during the setup process you should do so manually to prevent unauthorized access.
If you use the Start icon for ARIS Cloud Controller (Start > All Programs > ARIS > Administration > ARIS Cloud Controller) you can change the password command line parameter within the ACC shortcut. If you do not change the password it will be prompted every time you start ACC.
If you run an ARIS server setup after you have changed the password, enter the changed credentials.