Chocolate Ganache question

I recently tried to make two different ganaches one with dark and one with white chocolate. I did a 4 to 1 ratio chocolate to cream into order to make the ganache stuff so I can cut it with a knife into squares and did them. My problems1. The white chocolate ganache wouldn't harden unless I put it in the fridge and when I took it out it went soft again. How do I make it stiffen at room temperature?2. I had the exact same problem with the dark chocolate but it was a tiny bit stiffer but still I had to chill it to make it stiff.The way I made these is I boiled the cream and poured it over the chocolate pieces. When melted I stirred and poured into a pan and let cool. How do I fix these problems? I want to be able to handle the ganache and work with it.
updated by @bryan: 04/10/15 11:43:37AM

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.

See I was not checking the temp of the cream when I poured it over the chocolate so I melt the chocolate at a temp that won't lose the temper then mix the cream in ?