Hi Fagel,
You can see this on an individual basis if you go to Invitee Management > Manage > Invitees & Registrants > Click on someone's name > Click on the View History link within their invitee record.
To see changes in bulk, you can create a custom report with the report type of "Invitee Change History."
For travel changes, you can run the standard reports of "Hotel Request Changes," "Hotel Request History," "Air Request History," and "Air Actuals Changes."
Best,
Julia