For convenience, once Price Alerts are enabled, all the currencies you’ve transacted in previously will be automatically followed.
You can manage these settings by following the below steps:
1 - Tap Markets at the bottom of your home screen
2 - Select your currency
3 - Tap the star at the top right corner to follow or unfollow a currency
4 - When you're in the Markets page, you'll see a yellow star near the currencies you're following
You can see all the currencies you're following at the Markets page under "Following".