Overlapping walls: edited mesh doesn't recalculate array modifier results Trying an old Blender Guru tutorial 'how to create a high-rise building' I came upon a change I needed to make to the length of the original wall mesh. After setting the length of original mesh I applied a mirror modifier, array modifier to get four walls (offset is an empty that i rotate) and an second array for getting the 14 floors of the building. However the two left windows of the original mesh were to small (rectangular and not square). I tried to change the length by grabbing the right side of the mesh (selected). The thing is now the walls are overlapping instead of getting a larger building as a result of expanding walls. What are possible solutions?

My blend file can be found at: PasteAll
The mirror modifier works by taking into account where the geometry is in relation to the object origin (the orange dot at the centre of the model). The array modifier that controls where the walls are depends on the chosen Empty, which is at the same place as the object origin.

All you have to do is select all the geometry in edit mode and move it on the 'Y' axis (green), away from the object origin (by pressing G, Y) and both the Mirror modifier and the Array modifier will update.