I've always been able to choose a drive letter for a USB drive that Windows will retain/remember and continue to use when that drive is connected. This includes Windows 10. However, just recently this stopped working on Windows 10. This is an important capability for certain drives.
I have some suspicion that the problem could be related to a recent desire to replace such a drive with a new one. In that, a drive formerly using this drive letter is removed and replaced by a new one. When removing the old drive Disk Management was used to remove the drive letter. When the new drive was connected Disk Management was used again to assign the previously used drive letter to the new drive. While Disk Management behaved inconsistently I was able to get the drive letter assigned to the new drive. However, when the computer is shutdown & rebooted that assignment goes away and Windows seems to assign the drive letter in the manner it would for a device that never had a drive letter assigned via Disk Management. Having to rerun Disk Management every time the computer is rebooted is quite annoying.
Would be grateful for any ideas about how to rectify this failure?