Hello, @Dmuz.

Changing the platform from 32 bit to 64 bit or the other way around needs to uninstall and reinstall the application. At this time, you can start by uninstalling your Excel Office 365 and reinstalling it.

If you wish to, you work with a professional accountant to help you install the application successfully.

As always, check out our help articles in case you need tips and related links while working with QuickBooks in the future.

I'll be right here to help if you have any other questions. Just add a comment below. Have a great day!