- name: Change "admin" password
  isam:
    appliance: "{{ inventory_hostname }}"
    username:  "{{ username }}"
    password:  "{{ password }}"
    lmi_port:  "{{ lmi_port }}"
    log:       "{{ log_level }}"
    force:     "{{ force }}"
    action: ibmsecurity.isam.base.admin.set_pw
    isamapi:
      oldPassword: "{{ old_password }}"
      newPassword: "{{ password}}"
  ignore_errors: true
  when: old_password is defined
  notify: Commit Changes

- name: Change "admin" password
  isam:
    appliance: "{{ inventory_hostname }}"
    username:  "{{ username }}"
    password:  "{{ old_password }}"
    lmi_port:  "{{ lmi_port }}"
    log:       "{{ log_level }}"
    force:     "{{ force }}"
    action: ibmsecurity.isam.base.admin.set_pw
    isamapi:
      oldPassword: "{{ old_password }}"
      newPassword: "{{ password}}"
  ignore_errors: true
  when: old_password is defined
  notify: Commit Changes

Use old_password to authenticate with ISAM
Use old_password to authenticate with ISAM