To change the currency on your collection, please go to Profile, then Settings and there is an option there to select currency.
On iPhone:
Go to Profile (bottom right in menu bar)
Tap on the Settings gear in the top right
Scroll slightly down to "Profile" and you'll see Currency as the last option
Select the currency you'd like to change it to
It will auto save
On the desktop site:
Click on your profile (top right of screen)
Click Settings
Scroll slightly down to "Preferences" and you'll see Currency
Change the current currency to any other in the list, or type in your currency
Changes will save automatically and you'll see a confirmation notification