It is not necessary to return to the Timeline to edit an Event. This can also be done from the charts in Dashboard or Lets See.
Click on the event and then click the banner- highlighted.
This brings up the edit event dialogue.
You can edit the Name , Owner, Type (icon) and Timing. You can also delete the event (by clicking the bin symbol) if its not linked to another item in the plan. Click done when you have finished editing.