Click on the button with the name of the dinosaur you want to transform, then click the different DNA samples to change it. NOTE: Say you're using velociraptor and you click T rex and then Unknown, the Indoraptor comes up, but it has nothing to do with how you had already done T rex. So, the Indoraptor is just Velociraptor and Unknown, not Velociraptor, T rex, and Unknown.
I know it says this is a remix but I didn't keep anything from the original except the basic idea of making hybrids.