Oracle getting started Tutorial: handling User Password Expiration

The following error is reported during database Logon:
ERROR: ORA-28002: the password will expire within 7 days
The default profile of Oracle before 11g has no restrictions on password expiration. in Oracle 11g, the default profile enables the password expiration time to be 180 days. You can remove this restriction.
Query the Password Expiration parameter settings of the default profile.
Sys @ www.bkjia.com> select * from dba_profiles where profile = 'default' and resource_name = 'password _ LIFE_TIME ';
PROFILE RESOURCE_NAME RESOURCE LIMIT
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DEFAULT PASSWORD_LIFE_TIME PASSWORD 180

Set the default profile password to never expire. It takes effect immediately and does not need to be restarted.
Sys @ www.bkjia.com> alter profile default limit PASSWORD_LIFE_TIME UNLIMITED;
Profile altered.
For expired instances, You need to reset the password, which is the same as the previous password.
Sys @ www.bkjia.com> alter user APP identified by xxxapp;
User altered.

By the way, I will explain the password-related parameters:
Sys @ www.bkjia.com> select * from dba_profiles where profile = 'default' and RESOURCE_NAME like 'password % ';
PROFILE RESOURCE_NAME RESOURCE LIMIT
---------------------------------------------------------------------------------
DEFAULT FAILED_LOGIN_ATTEMPTS PASSWORD 10
DEFAULT PASSWORD_LIFE_TIME PASSWORD UNLIMITED
DEFAULT PASSWORD_REUSE_TIME PASSWORD UNLIMITED
DEFAULT PASSWORD_REUSE_MAX PASSWORD UNLIMITED
DEFAULT PASSWORD_VERIFY_FUNCTION PASSWORD NULL
DEFAULT PASSWORD_LOCK_TIME PASSWORD 1
DEFAULT PASSWORD_GRACE_TIME PASSWORD 7
FAILED_LOGIN_ATTEMPTS integer
Set the number of failures that can be performed when logging on to the ORACLE database. Once a user attempts to log on to the database to reach this value, the user's account is locked and can only be unlocked by the DBA.
PASSWORD_LIFE_TIME
Set the password validity period (number of days). Once the password expires, you must reset the password. The default value is UNLIMITED.
PASSWORD_REUSE_TIME
Many systems do not allow users to re-enable previous passwords. This resource item sets the number of days after which a password expires before the user can use the password again. The default value is UNLIMITED.
PASSWORD_REUSE_MAX
The number of times that a previously used password must be reset before it is re-enabled ).
PASSWORD_LOCK_TIME
Set the number of days when the account is locked (when the logon fails to reach FAILED_LOGIN_ATTEMPTS ).
PASSWORD_GRACE_TIME
Set the number of days before the password expires. If the password is returned after it expires, a warning message is displayed during logon, indicating the number of days. If the password is not modified within a grace period, the password will become invalid.
PASSWORD_VERITY_FUNCTION
This resource item allows you to call a PL/SQL to verify the password. ORACLE has provided scripts for this application, but users can develop their own verification scripts as long as they wish. This parameter is set to the name of the PL/SQL function. The default value is NULL.