In Nastran, this ic controlled by an EIGRL bulk data card referenced by a METHOD card in case control.
For a METHOD in the global case, edit the solution in NX. In the Case Control section, define a Lanczos Data Modeling object. This object allows you to define min and max frequency, number of modes, and all other fields on the EIGRL card.
For a METHOD in a specific subcase, edit the subcase and select a Lanczos Data modeling object in that location.
If a different method is defined in each location, the one defined in the subcase is used for the analysis.