The SimScale workbench or GUI currently only allows users to vary one parameter at a time. As soon as you input a table for one parameter, the other input variables are blocked from being assigned multiple values. This is to prevent users from inadvertently starting a large number of runs which can quickly consume very many core hours. As an example, if a user provides 4 different values for three different parameters, that amounts to 4^3 or 64 simulations.
It is possible to carry out multi-parameter studies using the SimScale API. The API offers a number of different automations, such as simultaneously loading different geometries and starting multi-parameter studies.
For more information on the the API visit this page: The SimScale API
For more information on parameter studies on the SimScale workbench: How to Run Parametric Studies in SimScale?