Oracle: Forgot to configure password ____oracle

Cmd->sqlplus "/as sysdba" command line login Oracle
At this point you can see what the default account, this step can be omitted.
Cmd->select username from dba_users;//No semicolon will show a "2" on the next line, because sqlplus each command should end with a semicolon.
Cmd->alter user sys identified by oracle;//can change the password of the SYS account and then use it.

Https://localhost:5500/em/login log in using the SYS account.

User	Password	Description
SYS	Determined at installation	Perform administrative tasks for the database, with the data dictionary of the instance under SYS
Sysman	Oem_temp	Enterprise Manager Account
SYSTEM	Determined at installation	Used to perform database administration tasks with a small number of instance objects