I've been searching for a solution to the lack of space in my C drive, and I'm totally surprised by the abundance of people out there with same problem... and the fact that Evernote still hasn't fixed this issue after all these years.
However, the workaround provided by Loster2 there works like magic! I uninstalled Evernote from my desktop, and then manually deleted the backup folder (located in C:\Users\User\AppData\Roaming\Evernote\resource-cache). Then I reinstall Evernote without connecting to the internet. After reinstalling, I created a new folder in my D drive with the same name as what's originally in the folder mentioned above (should start with "User" then a bunch of numbers). Then I drop the symbolic link of the created folder into the folder mentioned above (should now exist after reinstalling Evernote) and replace the original folder. And now, after connecting to the internet, you can see the backup files slowing being synced to the folder in your D drive! That's how I moved 32G of files to my D drive finally...
