Check your key settings. There should be some for using your morphs. The Morph mod's defaults are slash "/", and the two square brackets "[" "]". When you're in the morph menu, scroll up and down or hold the shift-key + scroll up and down.
By the way, you could have found all this out yourself by looking at the web page for the Morph mod. That's how I got it.
By the way, you could have found all this out yourself by looking at the web page for the Morph mod. That's how I got it.