Your currency settings apply to all items in your inventory. You can set or edit your default currency at any time, in either your mobile or desktop app (settings applied in one will apply in both.)
To change your currency setting using the desktop app:
From the menu on the left select Settings > Inventory Settings.
Go to Currency and select your default currency from the drop-down menu. This will change the currency on all existing items without conversion. For example: your currency is USD and you have set an item price to $10. If you then change your default currency to GBP, that item price will now show as £10 – no currency conversion will be performed.
To set or change your default currency using the mobile app:
Tap the three stacked lines ☰ icon in the top left corner of the screen to access the app menu, then
tap Settings > Currency and select your default currency.
Tap the arrow icon < at the top left of your screen to apply the change and go back.