This toolbox is opened via the Window > Standard Toolboxes menu.
It allows you to set default settings for the operation of Snap and Lock modes.
Snap Settings Toolbox
Settings
From the pulldown list a standard setting can be selected. The settings are stored in the Master Tool Settings. You can make a temporary override to the settings shown by pressing edit button 
and changing the values shown in the Snap Settings form.
The values below will override the defaults defined in the settings selected from the pulldown list and the setting name will change to <User Setting>.
Offset snap radius
This is the setting which is applied to the Snap Offset tool and corresponds to the radius of the circle displayed around the cursor when this tool is activated.
From end snap distance
This value applies to two different snap modes. It is either the offset from the end distance, which is applied to the Snap From End tool or the offset the intersection distance applied to the Snap From Intersection tool.
Arc segments
This is the value which is applied to the Snap Quadrant tool and corresponds to the number of points on a circle that can be snapped to.
The above values will override the defaults defined in the settings selected from the pulldown list.
Related topics: Draw - Snap - User Settings, Notes On Standard Toolboxes