Multicurrency is available as an advanced feature within QuickBooks Online. This feature tracks your foreign currency transactions including any exchange gains or losses you might incur.
For countries where we offer multiple versions of QuickBooks Online, multicurrency is available in our Essentials and Plus versions. If you don't see the Currency section in the Advanced tab of Account and Settings (or Company Settings), and you have customers and/or suppliers that deal in a currency different than your local currency, then you'll have to upgrade the version of QuickBooks that you're currently using.
You have to turn on this feature before you can use it. Once it is turned on, you cannot disable it!