Method 1:
Step 1: login first
Step 2: On top right, select Help->Change Password menu.
Step 3: In the pop up window, input your old password and new password.
Step 4: Press OK.
Or
Method 2:
Step 1: Login first
Step 2: Select System->User menu
Step 3: select the username in the user list and click ‘Modify Password’ button.