Location of Modify Truss Elements Command
Click the Truss icon in the toolbar with the left mouse button.
Click the Modify Truss Elements command in the auxiliary toolbar that opens.
Select the elements whose truss section you want to change from the perspective screen and click the right mouse button.
Determine the truss section of the elements in the settings window.
Click the OK button.
Selecting the element to be changed on the perspective screen
Change the cross section in the steel settings dialog that opens