How to change SYS and SYSTEM passwords on Oracle Database 11.2

Hi All,
I would like to ask you about a way to change SYS password.

I already read through Document#1051982.6, which tells you should run ALTER USER command to change SYS password on Oracle Database Version7.0.16.0 and later (including 11.2)
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　　Document ID 1051982.6
    How to Change SYS and SYSTEM Passwords
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However "Oracle Database Security Guide 11.2" says about changing SYS password like below:
( 2-9 Managing Security for Oracle Database Users "Changin the SYS Uer Password" Section)
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"you should use the ORAPWD command line utility
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Do not use the ALTER USER statement or the PASSWORD command to change the SYS user password.