I am not sure that you have moved the library or merely copied the folder.
The problem is that some software uses the libraries as default folders for saving files and if you have merely copied the folders rather than changed the library location this software might still use the C: drive location.
Looking at a Windows explorer will tell by the folder symbol.
You don’t mention how big the two drives are, however, the SSD is going to be noticeably faster, compared to the hard drive, so I’d make the following suggestion.
Don’t agree with this, SSDs have limited read write cycles and are better used for files that are not varied much (such as Program and OS files) whereas a HDD drive are far more robust and quick enough for loading/saving the much smaller user files.
SSD vs HDD Speed and Performance Comparison (Updated 2021) (wintechlab.com)
I can only judge by the comparisons (and personal experience).
Don’t forget that a hard drive has to search for bits of files, moving the read/write heads, which could be all over the surface, whilst an SSD works more like a memory card.
That’s why you defrag HDDs regularly
Was not, really, a problem once bigger Hard Drives became normal.
I wouldn’t have bothered to defrag a 550Gb HDD drive, for example, as there is plenty of space for my needs, without having to use things like Defrag to clean it up very often.
As for SSD, no to Defrag. (says the manufacturer).
No, I didn’t move ‘Progam Files’ either by copying or moving. Comparing it with the one which remains on C: which contains lots of different files, the one on D: contains only that ModifiableWindowsApps which contains nothing.
As I said, presumably a ‘Windows flaw’!
I haven’t quoted all the subsequent posts, but just to add that I was told earlier that the HDD and SSD will both load files quickly, and have found this to be the case.
The HDD is about twice as big as the SSD and, interestingly, is already named ‘Data’, so I assume it is normal to put the files there and programmes and Windows on C:
It’s working anyway.
Incidentally, I have never defragged the HDD (it didn’t have an SSD) on my old laptop anyway.
Anyway, I appreciate all the help you have both been kind enough to offer.
Just to drag this out a little further(!) I have found that Dropbox, which I found quick and easy to use, has now decided to change its interface.
It is now so much bigger, taking up most of the screen, but more importantly more clunky and awkward to use. I’d much rather go back to the earlier version, but I can find no means of doing so, or even contacting the Dropbox people to request that.
OneDrive has now got to be my preferential means of temporary backup for new files, though I’ve also been looking at Google Drive which also doesn’t seem as user friendly.
OneDrive is my preferred choice, too …
Yes, it is one of the really good things related to Windows.
Google Drive is something that I have running on my smartphone but, consequently, on my computer it is now full of things which don’t really relate to what I do on the computer and makes it a little more difficult to negotiate through. Perhaps I’ll get more used to it.
At one time, I was using Google mapping and photo apps a lot so it made sense to use Google Drive but then, when I started using MSOffice365, I got 1 TB of OneDrive cloud storage so I started using OneDrive to sync my MP3s between PCs (I have about 200GB of MP3s on external hard drives) - it’s friendly and fast …
I no longer use Google Maps or Photos so Google Drive is just for odds’n’sods, bits’n’pieces …
Can you still buy such a small drive? It seems to me that 2Tb is the smallest HDD you can get these days and 4Tb seems to be the average.
My last desktop was supplied with a 500gb SSD and a 4Tb HDD and that was over a year ago. You shouldn’t backup on the same machine either that goes against all expert advice
Perhaps it’s different over there, but my 500Gb SSD + 1Tb HDD laptop seems to be pretty usual here.
It is certainly more that I need as, prior to moving my files to the HDD, everything on my laptop amounted to less than 300Gb and was accommodated completely on the SSD.
As for backing up, I back up temporarily to OneDrive and Dropbox (though I might ditch the latter as I’ve gone off it since they changed!) and then regularly to two external hard drives. So even if my laptop goes up in flames, or is nicked, hopefully all my files should be recoverable!
I think it is just a matter of economy of scale, 4Tb is far too large even with lots of photos and videos but the difference in price between a 2TB and 4Tb HDD is peanuts. from memory the bigger drive added about $60 to the cost of the computer (a Lenovo Legend)
And mine. The synchronisation between my PC files and Google Drive was diabolical and used either to take forever, or it stalled completely. One Drive is almost instantaneous and very quick.
But if it’s not needed, and probably never will be, that $60 (£20?) would buy me a few pints! 
Yes, I agree. OneDrive is the best as far as I’m concerned, despite it being from Microsoft!
Fair point, but I buy the beer anyway
Well if you’re buying…
