Understanding Sage 50 Cloud Ex Rates

SOLVED

Hi all,

I'm brand new to Sage 50 Cloud and trying to understand how it uses ex rates (GBP/EUR).

It seems I can fix an ex rate, and all transactions will use that rate, unless I specifically overwrite it for that transaction. 

What I really want is to set a rate at the start of each month and use that rate for any transactions in that month. 

Can this be achieved by simply changing the master ex rate at the start of each month?   Or does that cause issues elsewhere? 

If I needed to enter a previous months transaction for some reason, could I then simply overwrite it to the relevant months ex rate for that one transaction? 

Or is there a better way to set the whole thing up?

We'll be issuing sales invoices, receiving payments, entering purchase invoices and making payments in both GBP and EUR.  We'll also be running GBP and EUR bank accounts.

Any help would be greatly appreciated!

Many thanks

Paul