Sometimes we may find the Osnap is not very sensitive, and you have to move the cursor right on top of the endpoint or midpoint to catch it.
To change the object snap sensitivity, we can use the APERTURE system variable.
The APERTURE system variable is used to set the display size of object snap aperture box by pixels.
The default value for APERTURE is 10, shown as below, its range is from 1 to 50, the larger the number, the bigger the aperture box.
The APBOX system variable is used to control whether to turn the auto snap aperture box on or off. Value 0 is off while value 1 is on. The aperture box displays at the center of cross cursor when snapping objects.