How do I reuse an existing File History backup as a backup target?

Question

All I wanted was to do a File History backup to a USB connected drive, which had previously been backed up to as an SMB network share. Because USB is faster. The list of directories to include/exclude in the backup was already set up and the entire backup directory structure was already present, so basically an open goal, or so I thought.

The current path to my backup folder (which is consistently being ignored) is simply D:/<username>. I didn't choose that ambiguous path — File History did, some time ago.

Windows 10 Settings

1. File History first tells me that I have to "stop using the current backup drive" if I want to add another one. Weird (for a backup utility to discourage redundancy), but ok, I click "stop using drive" to stop using the SMB share as a destination.
2. After holding File History's hand all the way through so that it will even detect the USB drive (a whole project of its own) I'm finally allowed to select it. I add it as the backup destination.
3. File History has now deleted all my settings. All of my included/excluded paths to backup are gone...

...What?

After this I couldn't think of anything other than why all my settings had gone. It was only by chance that I later discovered that they're kept as part of the actual backup on the destination drive, and that File History had created new sets of backup folders in D:/FileHistory/<username> — instead of reusing the existing one — for every time I tried to add the drive as a backup target. Since I was also never offered the choice to reuse the existing backup when adding the drive I have to conclude that it won't reuse any folders without manual intervention.

Control Panel

By chance (again) while reading this answer I discovered that there are two GUIs for File History. I tried out that answer:

1. It says "File History is inactive" in "System and Security > File History", which is correct
2. I select the drive under "Select Drive" and click OK
3. I'm immediately redirected back to "File History" without being asked anything at all. No checkboxes exist or appear anywhere in this flow despite the linked answer suggesting otherwise
4. The window still says "File History is inactive".

Not what I expected.

If after this I click "Activate" in File History it immediately creates new folders on the drive without asking me to reuse the old one. That's no different from the behavior of the Settings app, contrary to the expectations set by the linked answer above.

My question is: how do I reuse the existing backup folders to continue my backups? I don't want to have to create new copies of every file every time I add the drive as a backup target, regardless of whether it's via USB or SMB.

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I realize that I'll be told to use another backup tool, but that's a new project altogether and I want to make sure I have a working backup first, before spending even more time on finding a replacement.

Answer 1

Unlike Backup and Restore where I couldn't move anything anywhere once I had made a backup, and still have the tool recognize it, it appears that File History allows me to move the backup target folders around.

Simply moving the username folder into the auto created FileHistory folder (after deleting the existing one in there) will allow me to select it as an existing backup target in Control Panel.