To Set the Snap Mode Override via the Snap Mode Toolbox

(Optional) If the desired snap mode override is not visible on the docked Snap Mode toolbox, select it from the pop-up menu.
On the toolbox, double-click the desired snap mode override.
The Snap Mode override's button is highlighted with light gray; while the active Snap Mode's button remains highlighted with speckled gray.

Snap Mode button bar showing the active snap mode highlighted in speckled gray, and the override snap mode to the right highlighted in light gray