Change default store

We have set up multi-store in OCv1.5. Store1 is default store, is there anyway could change default store to store2?

Which "1.5"? They range from 1.5.0.0 through 1.5.6.1 . . .

Search button top right asked change default store returns "About 4,580 results (0.33 seconds)" at
https://www.google.com/search?q=change+ ... encart.com
and several speak to what you asked.

Extensions button top right asked change default store returns several possibilities at
http://www.opencart.com/index.php?route ... lt%20store
and one, representative, is named Rename "default" store name.

That's what the two buttons are for -- showing how questions that have already been asked have been answered.