one column or full-widht on start page

hello,
the theme is great, i like it very much, but:
i have tried now for the all day to change the page to fullwidht. although I’ve selected the template, it doesn’t appear as selected. it works on every other page, but not on the “shop” (main) page.
i would appreciate very much if you could give advice in this case.
http://www.minmuzz.ch
thanks in advance,
thomas