Each data column has a set of column properties. The Response Limits property defines the desirability. This definition can be entered with the response when designing the experiment, for example DOE > Custom Design. It can be defined in the Graph > Profiler and then saved as a column property. It can be directly added to the data column from the data table.
Each response may have its own response limits as necessary. The optimization of factor settings is the result of maximizing the joint desirability of all the responses. Each desirability can have a weight, Importance, when necessary. The desirability is unweighted by default. That is to say, all the responses are equally important to determining the optimal levels.