When working with text in Photoshop, there are several steps needed when you wish to change the text from 2-d to 3-d. You need the Transform function. This is because you are no longer going to be working in layers. You are dealing with a shape as 3-d is perceived differently because it now has perspective, which 2-d does not.
Therefore this 3-d text has to be constructed differently in this application. You should go to the Transform Pathway and choose Perspective to create your 3-d text.