Hi Kon
As you see, the attachment control is variable so as it expands it pushes the lines longer and if they reach the end they need to wrap.
Add a layout table that is 3 cells wide and try putting each control in the layout table and that should stop the wrapping. Some of the filled attachment control will be cut off or expand horizontally.
Otherwise only go two wide.
Another way would be to use a section around each but a layout table would be best. They are available in your task pane on the right.