– if you are referring to transaction currency, you may add Amount (Foreign Currency) field
– if your account is OneWorld and the currency you would want it be presented is one that of Parent (/Grandparent..), then you may:
1. On reports, run the consolidated level on the Subsidiary Context then add another filter which is Subsidiary : Name then set it as appropriate
2. On searches, use the Restrict View feature under Home > Set Preferences and use the subsidiary and set under Result : Consolidated Exchange rate = Per account
– if it is on the currency which is none of the above, I believe it has been logged as an enhancement request already
– if you're using OneWorld, you may want to check the Multi-book feature