I've successfully installed the mod, but my computer cannot handle the settings I chose. Every time I start a new game and go through the trapdoor into seyda neen, the game crashes.

How can I change those settings?

First off lower all graphic settings to absolute zilch and see if it's too many new graphics causing the crash. If it is then load the esms/esps separately until you see which ones are doing it. As you are starting from a new character you should be able to test it easily enough without much loss.