If you see different currencies in the Profit Calculator panel, you may be viewing a listing for one marketplace while your home marketplace is set to another in Settings - an example is below:
Here, a user selling in the German marketplace has the Cost Price in EUR and the Sale Price in GBP; as they are buying the product in Germany with EUR and considering a sale in the UK via the European Marketplaces panel, the GBP currency for the UK will populate the Sale Price, (since the potential revenue made would be in GBP).
For information on configuring your home marketplace, click here; to learn more about the European Marketplaces panel, click here.