The merchant account ID is listed under the Settings > Processing page.<br />
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<b>Note:</b> By default, Braintree does not support multiple currencies. The currency value you may select for your purchasable items <b><i>will be ignored</i></b>.<br />
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To support multiple currencies, you need to set this up by <a href="mailto:support@braintreepayments.com">contacting Braintree</a> and ask them to create multiple Merchant Accounts. It is the Merchant Account which dictates which currency transactions will be processed in. You must specify which Merchant Account to use here.