Windows 10, allow saving files to a USB hard drive on same computer

The problem that can show up in an application (Word, Excel or whatever else), that "you don't have permission to save to this device" can be fixed by, first of all, changing the advanced sharing settings of the device. I changed to group Everyone (who is logged into the computer) having full control. In File Explorer, click on the external hard drive in question, then on Properties at the bottom. Click on Sharing on the Properties page, then on the Sharing tab and Advanced Sharing. Here you give a share name (I used the drive letter) and permissions - I specified Everyone and selected all the permissions).

Now you should be able to save into any folder, But if a folder has a Read-Only property, you have to also change that. I found that I could only take "read-only" status off and have it stick after I had changed the USB drive's Advanced Sharing as just described.

Of course you must have Administrator privileges to do these things. I described steps in a non-Workgroup procedure. It may be different for computers in a Workgroup.

There has been lots of confusion about this problem in various online forums. Hope this helps.