Hello:

 

So I have downloaded a bunch of CDLC songs into Rocksmith that suppord Dynamic difficulty. However, every time I play a song, it shoots all the notes at full to me.

 

Is there some kind of configuration or something? Because of this, I have to stick with the songs that come with the game in order to improve my skill.

Look at this thread below. I just quickly searched and found this, hope it points you in the right direction.

 

http://customsforge.com/topic/20321-changing-difficulty-level/#

Some of the songs you downloaded might have DD and some might not.  The ones that don't, you can add DD using DD Creator with Rocksmith Toolkit.  If they already have DD, you can adjust the starting difficulty by hitting space bar during the song and adjusting the difficulty level in Riff Repeater.