In Microsoft Windows Operating Systems (Windows 7, 8 & 10) all user files are stored by default under several Personal folders (Documents, Downloads, Favorites, Music, Videos, Pictures, etc.) at the following location on the main disk (OS disk): C:\Users\<USERNAME>\
If your personal files exceeds the main disk’s limits and you have an additional drive or partition on your system with enough free space, then you can move your files from your main disk into the additional drive by using the “Move” feature, but If you have problems when using the “Move” feature, then you can use Windows Registry to set a different location for your personal folders.
The Personal folders settings per user are stored at the following registry key:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
Firstly, unless you are very confident with your IT skills, I do not advise to make any changes to the registry file.
Also, before making any changes, do make a backup of your registry file.