4 to 1 ratio for dark chocolate is overkill. 2 to 1 is more realistic. Are you adding other ingredients? What is the temp of your ganache? Putting in fridge temporarily helps, but it will soften more when you bring it to room temp. Try to not get your chocolate out of temper and it will set up nicely at room temp. White chocolate is a bit trickier. 3 or 4 to 1 is normal. I start with melted white chocolate and pour the cream over it at about 115F. What is the cocoa butter content of your chocolate? It is the CB that sets the ganache.