Hi,
if you go to html/com_k2store you will find files overrided default template. As I remember version of k2 store was 2.5.1 (becasue template isn't supported any more) and you update it to 3.0.3. You have to compare default files from 2.5.1 and 3.0.3 using for example WinMerge tool. And make changes in overrided files. Or change this folder name for a moment and check if default view is ok for you.