QuickBooks multi-currency problems in both Desktop and Online versions can disrupt financial accuracy and reporting. Common issues include incorrect exchange rates, currency conversion errors, and improper account setup. To resolve these, ensure multi-currency is enabled, update exchange rates regularly, and verify account settings. For Desktop, use the QuickBooks Tool Hub to fix issues, while Online users should check the currency settings under Account and Settings. Regularly review transactions for errors and ensure third-party integrations support multi-currency functionality. Proper setup and maintenance are crucial to preventing and resolving multi-currency problems in QuickBooks.