How to change password for user `polardbx_root`

mysql>select user();
+--------------------------+
| USER()                   |
+--------------------------+
| polardbx_root@172.17.0.1 |
+--------------------------+
1 row in set (0.00 sec)

mysql>select current_user();
+----------------+
| current_user() |
+----------------+
| d1@pxc-tryout  |
+----------------+
1 row in set (0.01 sec)

mysql>set password for current_user() = password('pXVwPKGrG');
ERROR 3009 (HY000): [154bfae7a9c01000][172.17.0.5:54645][d1]syntax error, error in :'password for current_user() = password('pXV', expect =, actual (, pos 30, line 1, column 30, token (

mysql>SET PASSWORD FOR 'polardbx_root'@'pxc-tryout' = PASSWORD('654321');
ERROR 3009 (HY000): [154bfb2645801000][172.17.0.5:54645][d1]Illegal host: pxc-tryout

mysql>SET PASSWORD FOR 'polardbx_root'@'%' = PASSWORD('654321');
ERROR 5107 (HY000): [154bfb2f25801000][172.17.0.5:54645][d1]ERR-CODE: [PXC-5107][ERR_OPERATION_NOT_ALLOWED] Can not modify polardbx_root since it is reserved for system

The report names no source files or tests; it provides SQL statements and server errors for changing the polardbx_root password. Start by reviewing the handling of SET PASSWORD and the reserved system user behavior. Done means documenting the supported password-change procedure or clarifying that the operation is not allowed.