Activities
The timeline groups activities by day. A record with many activities is hard to read. The filter narrows the timeline to what you need. This guide shows how to filter and view activities.
The filter row holds four controls:

FlyCRM updates the timeline as you change each control. The timeline shows only the activities that match.
To see all activities again, set each control back to its default. Set the type to All types and the user to All Users. Delete the text in the search box.