hi, you have a few options:
1. sign a message with your current withdrawal address that says "I am [username], please update my bitcoinmax withdrawal address to 1xxxxxyyyyy..." with the new withdrawal address (of the buyer).
OR
2. send a small amount (eg 0.00059) from your current withdrawal address, to the new withdrawal address, and let me know.
OR
3. send an amount greater than or equal to the full balance of the account plus interest, to your withdrawal address. this transaction can come from anywhere and anyone, as long as it covers the whole account amount and as long as it goes to the current withdrawal address (then after that you can send it wherever you like). and PM me with the new withdrawal address.
thanks.