If Multi-Currency setting is activated will this have an impact on past transactions? Can Eur payment invoice booked & settled with Usd bank a/c without a system error.

Activating the Multicurrency feature will not affect any past transactions that have already been recorded, Dilantha. Let me explain further.

With the multicurrency functionality, you can record transactions in various foreign currencies. Once this feature is activated, it cannot be reversed. This ensures that all currency conversion data remains consistent and accurately accounted for within the system going forward.

For a comprehensive understanding of this feature, please refer to the article: Set up and use Multicurrency in QuickBooks Online.

If you have any additional questions, please feel free to leave them in the comments, and we will be happy to assist you.