To enable the tool- select ‘Ghosting’ from the tools menu.
Select 'Enable Ghosting' and set the number of frames you wish to view the annotations behind or ahead of the current frame.
You can also set if you wish to save the ghost annotations on a frame when saving the frames out. So in the example frame above, with saving the ghost annotations on a frame enabled, the saved frame would show the numbers 1, 2, and 3, whereas when disabled, only the number 3 would be saved on the frame as that is what was annotated on the actual frame.