Symbol Terminal Magnet EditorTo edit a terminal magnet first select it. If the terminal magnet is on a schematic (project) then you will need to use sub-pick to select it.
A selected terminal magnet
Drag either of the terminal magnet's corner manipulators(
) to change the corners or ends.
Drag any scale manipulator to re-size the terminal magnet.
Drag the border to move it.
Terminal Magnet Properties Dialog
You can also edit the parameters of the border using its properties panel as shown below. To view the properties panel first select it.Then right-click on it, then select Properties Panel from the context menu that opens.
The Symbol Terminal Magnet Properties Editor
X
The X coordinate of the center of the border.
Y
The Y coordinate of the center of the border
Width
The width of the border.
Height
The height of the border
Reset Color
Click the 
button to reset the fill color.