Here is a post where this question is discussed
https://answers.laserfiche.com/questions/116789/Last-Person-to-Edit-Forms
In short, you can see the most recent user to modify a form in Forms itself. You can also check the database for this user. Forms does not keep a running list. If you want to keep a running list of who updated the form and when, you'd have to set up database triggers to monitor these database fields for changes and store a table each time those values are updated. This is effectively creating your own audit tables using the Forms database.