Well this is what mine looks like: https://memberservices.optuszoo.com.au/ms/user_management/change.htm
Step 1, select the sub account, Step 3 enter the new password twice.
Thanks Callum, that works. I was trying to do it from My Account - but that site does not allow a change of pword if you have forgotten it, but Member Services is different.
There is NOBODY to speak to. They divert you and you have to be dyeing to speak to an overseas person. A great excuse to cut back staff. Everything is good until you requirer assistance. Then nothing.