To move an entire roof you need to select all roof segments, then click and drag it to where you want it. You can do this quickly using the Move Whole Element tool. Note that if you move your exterior wall layout, the roof will go with it, eliminating the need to move it separately.
To move an entire roof:
Click on one of the roof’s edges to select the roof.
Right-click and select Move Whole Element, or select Edit > Modify Elements > Move Whole Element.
Click and drag to move the roof, then release your mouse button.