Mountains aren't casting shadows. How do I fix this? It ruins my immersion 100% when I look down and see trees and whatnot casting shadows yet i look up towards the mountains and the sun is still behind said mountain.

Change bdrawlandshadows=0 to bdrawlandshadows=1 in the skyrimprefs.ini file. See if that helps

I have it on, it helped a little bit but the only difference i saw was themountain was now casting shadows on itself and only itself. no shadows were making it to the ground.

Ohh, those shadows. Not sure what to tell you there. Not sure if there is even a mod for that. Sorry