Problems with Nvidia GT750m

I have a XPS 27 newest version, everything is updated and it's running windows 8.1 When I try to play a game on steam and i go to video settings it won't allow me to choose my nvidia gpu. It just says intel 4600. This is so annoying and I don't understand why it isn't working because it shows up in device manager and everything seems fine. Please help!!!! 

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