With Netica’s undo feature it is easy to solve a decision net, undo it, change a utility value or a node table, and then re-solve the net to see how the optimal decisions and maximum expected utility are affected.
But what if you want to force a decision
node to have a certain decision function, and see how the other decisions
and maximum expected utility change? Just enter the desired decision
function for the node in its table dialog
box (or paste it in, since you are often obtaining it from a previous
solution of a decision net), select the decision node, and change it into
a nature node by clicking the 
toolbar
button while holding down the ctrl
key. Then solve the net in the usual way, and observe the changes
to the other decision functions and the change to the maximum expected
utility. Of course you can use ‘undo’ to return to the original
situation. In general, when you want to set a decision node to a
certain decision function while you continue your analysis, you temporarily
change it into a nature node.