One option to change materials in the structure is the Select Constituent Materials dialog, as described in the chapter Setting the constituent materials. Depending on the use case, there are other options available through the ProcessGeo module.

It is possible to Reassign Material IDs, to Reassign Materials and to Reassign the Material of a Material ID (this corresponds to the option in the Select Constituent Materials dialog).

To access the options for reassigning quickly through a shortcut, right-click on Structure in the Project Status section on the left side of the GeoDict GUI.

Alternatively, these options are also available from the menu bar by selecting Model → ProcessGeo → Reassign Materials & IDs.