Strange edits to our pdf form

Hi, I am from the IT department at C-A-L Ranch Stores, and we use jotforms for our employment applications. Sometime last week the pdf we receive with the completed applications was edited in a very strange manner by persons unknown. Is ther any way we can look in to who was logging in to our account and when those edits started?

The unwanted content linked to this form. Which appears to be disabled now.

https://form.jotform.com/ahplshl/recommendation

You can check the account activity logs following this guide: https://www.jotform.com/help/370-How-to-View-Your-Account-Activity-Logs 

You can also edit the PDF report following this guide: https://www.jotform.com/help/384-How-to-Customize-PDF-Submissions-Report 

I hope this helps.