If your fudge is too soft, it wasn't cooked long enough or at a high enough temperature. You can refrigerate it to help make it harder. If your fudge is too hard, you either cooked it too long or at too high of a temperature and there is nothing that can be done to save it. We suggest using the "soft ball test" when making fudge to help ensure proper cooking. See below.
What is the "soft ball test"?
It is a test to see if the fudge has been cooked to the proper stage. Before you start cooking, fill a small dish with ice water and set aside. After you have brought the recipe to a full boil for 4 minutes, dribble a few drops of the mixture into the ice water from a wooden spoon. After it cools in the water (about 10 seconds), you should be able to roll it into small ball with your finger tips. If you put it in your mouth, it will be slightly chewy. If it passes these tests, you are done and should remove the mixture from heat and add the remaining ingredients. Otherwise, cook for another 30 seconds and try the test again. Most of the time, cooking time will not exceed 5 minutes.