How do I change the Currency Base for my organisation

How do I change the Currency Base for my organisation

Hi 

I'm an Australian Based Company that charges and account in USD (US clients) 

I'm unable to change the currency base in Zoho Invoices

- it appears all options are "locked" and cannot be changed

Have followed any forums help topic I can find

but as above - all options are either locked or does not exist - 

this is a new organisation registered with Soho - there is zero data and still trying to get pass this step. 

so the question is does SOHO invoices support companies registered in one country but trades in other currencies? 

if so how do I set this up.

cheers,