Why does my message board always take me to the .co.uk domain every time I reply to a message?

[zettafamily]

my account was originally set up in the UK but we now live in Australia. i have changed all addresses and registration details. however every time I reply to a message it takes me back to the ebay,co,uk domain and then i have to log out and re-log on the Australia domain. mow do I change this annoyance?

thanks

Marcello