Main toolbar > Curve Editor or Dope Sheet > Navigation: Track View toolbar > Zoom
In Track View, the Zoom controls are available from a three-button flyout. You can zoom your view of time horizontally (Zoom Time), vertically (Zoom Values), or in both directions simultaneously (Zoom). Drag to the right or upward (Zoom Values) to increase magnification, or to the left or downward (Zoom Values) to decrease magnification.
Note: All three zoom modes work in Curve Editor, but only Zoom and Zoom Time work in Dope Sheet.
Tip: If you have a three-button mouse, you can also zoom uniformly by using Ctrl+Alt+middle mouse button or by scrolling with your mouse wheel in the Curve Editor.
Tip: You can also zoom exclusively in time (left and right) or in value (up and down) by holding down Ctrl or Shift respectively while scrolling with your mouse wheel in the Curve Editor.
Zoom—Zooms your view of time and values simultaneously. Zoom remains active until you right-click to cancel or click another option.
The Zoom button is yellow while active.
Zoom Values—In Curve Editor, zooms the contents of the keys window vertically. Drag upward to increase magnification, or downward to decrease
magnification.
Zoom Time—Zooms the contents of the Key window horizontally.