Multiple currencies must be enabled in your organization before you can install PSA. PSA can use Salesforce's advanced currency management feature or it can use its own custom currency rate tables for multi-currency conversions. If you are already using advanced currency management without any problems, you do not need to use the PSA multi-currency conversions.
Using Salesforce Advanced Currency Management
If you want PSA to use Salesforce advanced currency management:
Ensure that the values in the Use Dated Exchange Rates and Use Salesforce Advanced Multi Currency configuration options in the Currencies configuration group are set to true.
From Setup, click Administration Setup | Company Profile | Manage Currencies.
Ensure that Salesforce Advanced Currency Management is enabled.
Ensure that an active currency exists for each currency that you want to use in your organization.
Ensure that the Corporate checkbox is selected on the currency that you want as your corporate currency.
Enter dated exchange rates for all the currencies that you want to use in your organization.
For more information, see the "About Advanced Currency Management" topic in the Salesforce Help.
Using PSA Multi-Currency Conversion
If you want PSA to use its own multi-currency conversion function:
Ensure that the value in the Use Dated Exchange Rates configuration option in the Currencies configuration group is set to true.
Ensure that the value in the Use Salesforce Advanced Multi Currency configuration option in the Currencies configuration group is set to false.
From Setup, click Administration Setup | Company Profile | Manage Currencies.
Ensure that Salesforce Advanced Currency Management is not enabled.
Ensure that an active currency exists for each currency that you want to use in your organization.
Ensure that the Corporate checkbox is selected on the currency that you want as your corporate currency.
Click the Currencies tab and add the currencies and dated exchange rates that you want to use in PSA. For further information, see Creating a PSA Currency.