Fields, once on an Attribute Cluster on the User Interface Canvas, can be reordered at any time, and can be moved both within Attribute Clusters and between Attribute Clusters.
In the first case, it is possible to move a Field from one position in an Attribute Cluster to another position in the same Attribute Cluster. To do this, click on the Label of the Field in question, and, holding the left mouse button down, drag it until it is directly over the Label of the Field with which it is to be positionally swapped. Finally, release the mouse button, and the Field will move to its new position.
In the second case, it is possible to move a Field from one Attribute Cluster to another Attribute Cluster. This will have the effect of removing it completely from the first Cluster, and adding it as the last Field in the second Cluster. To do this, click on the Label of the Field in question, and, holding the left mouse button down, drag it until it is directly over the middle of the Attribute Cluster to which it is to be moved. Finally, release the mouse button, and the Field will move to its new position.