can't get email

Secondary email accounts give error:  "unable to connect to POP3 server  ...  connect timed out."   Editing email preferences on secondary accounts without changing anything except to re-add password (which is missing again upon every new access) will fix it temporarily.  But problem resurfaces again and again.  Password is missing every time secondary account is edited and must be re-added in password field, despite successfully saving with it filled in.  Also, can't change port number -- it either says "Error: Your account information is incomplete" or it simply does nothing after pressing save button.