Freeze Non-Selected Curves

Track View > Curve Editor > Display menu > Show Non-Selected Curves > Freeze Non-Selected Curves

Freeze Non-Selected Curves makes all non-highlighted curves uneditable. Default=On. Freeze Non-Selected Curves is a selection modifier and has the following properties:

Non-highlighted curves display as dashed lines.
You can manipulate vertices on highlighted curves only in the Edit window.
You highlight other curves by clicking their icons in the Hierarchy list.

Turn Freeze Non-Selected Curves off when you want to be able to edit multiple curves without having to select them all. Turn Freeze Non-Selected Curves On when you have multiple vertices on multiple curves all in the same place.

Procedure

Example: To freeze non-selected curves:

Animate an object's position.
From the Graph Editors menu, choose Track View - Curve Editor. On the Options menu, make sure Auto Expand > Selected Objects Only/Transforms/XYZ Components are all on.

The X/Y/Z position tracks are all highlighted, and their curves appear in the Key window. You can drag keys on any curve.
On the Display menu, make sure Hide Non-Selected Curves is on. This is the default setting.
In the Hierarchy list, click the X Position track icon.

Now only the red X Position curve is visible.
From the Display menu, choose Show Non-Selected Curves.

The other two curves reappear, and are editable.
From the Display menu, choose Freeze Non-Selected Curves.

The Y Position and Z Position curves remain visible, but display as dashed lines.
Position the mouse cursor over a vertex on the Y Position or Z Position curve.

The cursor doesn't change to a crosshair, indicating that you can't modify the vertex.
In the Hierarchy list, click the Y Position track icon and then Z Position track icon.

All three remain visible, but in each case the two non-highlighted tracks display as dashed lines, and are not editable.