When your users edit member data, it is stored in the audit trail.
Run this report to see who is changing what data and when.
Club details audit
When a member edits any information on the "Club Details" page, the changes they make are stored in the club details audit. View this page to view this audit report.
Each time someone deletes an invoice, it is saved in that member's (who the invoice was for) audit trail. To view a list of your deleted invoices, run this report.