You can define conversion attributes and add transaction currencies for budgets and forecasts on the Currency Settings page.
Define conversion attributes for use in converting plan amounts in transaction currencies to project currency and project functional currency. When you plan for cost and revenue, you must define separate attributes for converting cost and revenue amounts.
The conversion attributes that you define for a financial plan type become the default conversion attributes for a plan type that you add to a project template or project. You can update conversion attributes within a project only at the plan type or plan version level. You cannot define conversion attributes for a project template or project.
When entry of plan amounts in multiple currencies is enabled, you can enter amounts only for the currencies listed in the Add Transaction Currencies table on the Currency Settings page. Oracle Projects automatically lists the project currency and project functional currency. You can add additional transaction currencies at any time. You can add transaction currencies at the project, plan type (in the context of a project), and plan version levels.
Other Sources
Multi-Currency, Oracle General Ledger User's Guide