Reset parameter estimate in Simulink Design Optimization GUI without manual entry?

Within an estimation task created using the Simulink Design Optimization toolbox there is a check box to enable or disable the estimate of each variable in the model. For parameters I want to remain constant during an estimation task I can uncheck the estimate box, but the value for parameters changes from the value shown on the "Parameters" tab of the estimate task (which can be reset using "Reset to Default Settings") to the current value of the parameter in the workspace.

How do I specify a constant value, or initial guess value of the variable from within the Control and Estimation Tools Manager GUI?

The only solution I have found is to set the value of the variable in the Matlab Command Window (or with a script) to change the variable's value in the Matlab Workspace.