Editing form objects is not much different from working with other types of objects. For more information, see Objects.
There is, however, one important difference:
Important: Form objects cannot be selected by left-clicking on them with the mouse. To select a form object, right-click on it.
Alternatively, you can also use the ribbon command View | Object mode 
to switch to Object mode in which form objects can also be selected by left-clicking on them.
Once you have selected a form object, you can edit it like any other type of object – for example, move it with the mouse, resize it, etc.
By right-clicking with the mouse on the form object, you can modify its properties with the entry Form object: Properties in the context menu.
For more information on the properties of form objects, see Form objects in detail.