The Documents folder (or My Documents, if you prefer) is on the system drive by default. Not a good idea, because if something goes wrong with that you lose everything. Fortunately, moving is easy.
Windows (10) places the Documents folder (or My Documents in earlier versions of this operating system) on the system disk by default. If something goes wrong with Windows and you have to restore an image or even completely cry out and start installing again, all files in that folder are irretrievably lost. The only way to save the files then is to build the drive in another computer before the restore or reinstallation (or use a USB-to-SATA converter) and locate the Documents folder via File Explorer. Not really useful, especially if you just have to do a mountain of work on the computer and are in a hurry. It is therefore important to move the (My) Documents folder to another disk or partition as soon as possible. Fortunately that is very easy.
Documents to another drive or partition
Start the Explorer and create a folder on a partition other than the c partition. For example, something like My Documents on the D drive or partition. Then click - still in the Explorer - with the right mouse button on Documents and then on Characteristics. In the window that opens, click on the tab Location and there on the button Move. Browse to the newly created folder on (for example) the D drive and select it, followed by a click on Select folder. In the window asking you to move the documents, click Yes. After everything has been moved - can take a while with a well-filled folder - your documents are now safe on the D-drive. If it is necessary to restore an image from an earlier date, you will not notice this at all in terms of documents. So nice.
Finally, a tip: save (My) Documents not on an external drive. The moment you don't connect it, Windows and many other programs that expect a Documents folder will get into trouble!
