The important thing to know is where the content is positioned in relation to the page layout, because changing the page layout does not take the content that was in that position along with it.
So in the screenshots above we have a row that is one column 12 wide in the first position, then in the second row we have three columns of 4.
If we move the row of three 4 columns to the top of the page, it might be reasonable to expect that the content would go with them and reverse the current layout.
But what will actually happen is the content will remain where it is in relationship to its position on the page.
Lets look at that.