Home currency data inconsistent, when I try to turn on multi-currency.

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 click the Help icon to connect with an expert (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.  For more details on how to reach them, click this link: How to get help with QuickBooks.