Design Animation > Design Animation > Design Animation Timeline > Changing the Timeline Display
  
Changing the Timeline Display
Click these commands on the View menu to change the visible timeline scale:
View > Timescale Zoom In–Drag a box around the area to view more closely.
View > Timescale Zoom Out–Use after Zoom In to incrementally see more of the timeline.
View > Timescale Refit–Resets the animation timeline.