Create a search which will show the count on how many times the Lead Source has been updated on a transaction record.

You may use the following Criteria and Results fields to see how many times you've updated the field Lead Source on your Cash Sale transactions, you may opt to add a Date Range if you prefer.

1. Create a Saved Transaction Search, List > Search > Saved Searches > New > Transaction.
2. Add the following Criteria:
- Type is Cash Sale
- Main Line is True
- System Notes: Field is Lead Source
- System Notes: New Value is not empty
- System Notes : Old Value is empty

3. Use the following on the Results Tab
- Document Number | Count
- Formula (Numeric) | Sum | CASE WHEN {systemnotes.date} <> {datecreated} then 1 else 0 end

Please note that this will show the number of transactions you've created wherein the Date Created does not match the Date you've set the value of the field Lead Source.