Automount is enabled by default in Windows. When enabled, Windows automatically mounts the file system for a new volume (disk or drive) when it is added (connected) to the system, and then assigns a drive letter to the volume.
If you disable automount, it prevents Windows from automatically mounting and assigning drive letters to any new basic volumes (disk or drive) added (connected) to the system.
Any previously connected disks or drives that have been assigned a drive letter will always continue to be mounted with their former drive letter whenever connected by default, even after disabling automount.
If you like, you can scrub to remove volume mount point directories and registry settings for volumes that are no longer or currently connected to the system. This will clear all assigned drive letters of any previously connected disks and drives that are currently not connected to your PC. This can be handy if you want to disable automount and also want to prevent any previously connected disks and drives from being automatically mounted and assigned a drive letter when connected again.
This tutorial will show you how to enable or disable the automatic mounting and assigning a drive letter when a new disk or drive is connected (added) in Windows 7, Windows 8, and Windows 10.