Shopify Marketplace Connect includes a free foreign currency management tool that allows you to list on overseas marketplaces where the local currency differs from that used for your Shopify store e.g. Your store currency is in USD but you've listed on Amazon Canada.
The default setting is for the currency manager to track currency rates and make pricing adjustments as the foreign exchange (FX) rate changes on a monthly basis but it's possible to change the frequency of the FX rate (price changes) or set your own custom fixed FX rate (that doesn't change).
Settings > Manage Currencies.
For further assistance, please reach out to firstname.lastname@example.org