formula to test for what field was modified in a record audit table

I have a dbf table that acts as a audit table and captures info when ever someone changes a field for any customer record. But it doesn't just capture the fields that were changed. When one field in a record is changed, all fields in that record are written to the audit table. The audit table captures the state of the record data before the person made the changes.

So what is the best way to compare each field in the audit table to identify which fields are different/changed from the previous instance? For example, the way the audit table is configured now is that if a customer record was modified and saved three separate times in the main database the changes will be written to the audit table, but instead of just capturing the changed fields, it captures all of them...and there is no way to quickly identify which field in the audit record was the one that was modified.