You cannot change default download location of the Metro IE 10, however, it helps by changing the download location of the desktop IE. Follow these steps to change the default download location to a location of your choice.
a. Open Internet Explorer 10.
b. Press CTRL + J to open View Downloads window.
c. Click on the Options link.
d. Click on the Browse button
e. Navigate to and select(highlight) the folder that you want IE10 to use as the default download location, then click on the Select Folder button.
f. Click on OK and Close.