Hi, I think it's a regression in 4.10.1 but the version is not yet on the bugzilla. A Debian user reported (http://bugs.debian.org/702645) that he couldn't change the desktop icons size. Xfconf works fine though, it's only an UI problem.
Seems to be duplicate of bug #9882.
(In reply to comment #1) > Seems to be duplicate of bug #9882. Indeed. *** This bug has been marked as a duplicate of bug 9882 ***