The History feature allows you to browse all the activities that have been made to a specific objective. These include all activities related to an objective or its key results, such as changed alignment, added key results and tasks, added tags, and so on.
To view the history of an objective and its key results, perform the following:
In the navigation pane, under OKRs, click All sessions.
Click the session, where the objective is located.
Click the objective whose timeline you want to view.
In the upper-right corner, expand the three dot menu and click History.
The history timeline of activities appears.
You can use the tabs Objective, Tasks, Key Results, and All activities to check the timeline history.