To view the history of changes (such as who has edited the item, and what edits they have made) for a single punch list item.
Go to your project's Punch List tab.
Click Edit next to the punch list item you would like to view Change History for.
Click the Change History tab. The number next to "Change History" indicates how many times the punch list item has been edited. You can view what exactly has been edited in each version under the "Changed" column.