The expiration of CU*BASE login passwords is controlled at the iSeries level. The CU*Answers data center uses 30 days, the Site-4 data center uses 60 days, and self processing credit unions can set their own period.
This is not to be confused with employee ID password expirations, which are credit union defined.
CU*BASE login password are reset via Tool #199: Change User Name/Login Password (Shortcut: userpw).