Hello and welcome to the Community, hisham-shamsudhe
Enabling multicurrency shouldn't cause any changes to the existing data in home currency.
So that we can investigate further, please share some additional details on the inconsistencies that you're seeing in QuickBooks.
If you'd prefer, you can also begin a chat or call our support team on 0808 234 5337 (Mon - Fri, 8 AM - 7 PM, free from UK mobile & landlines). The agents available here will have access to set up a remote screen share to view your data with you.
