I can't change my desktop background-image for my macbook air
Might be corrupted desktop preferences...
Make following steps:

Open the Finder

From the Finder Menu Bar click Go &gt; Go to Folder

Paste the following in this field:
~/Library/Preferences/com.apple.finder.plist


Click Go then move the com.apple.finder.plist file to the trash.
Restart your MacBook Air, then select a desktop background photo from System Preferences &gt; Desktop &amp; Screen Saver &gt; Desktop and then it should work.