How do i change the soundfont for the midis?

I like using Touhou.sf2, but i can't seem to figure out how to change the soundfont in eternity to Touhou.sf2. any ideas?

You need to set the SDL_SOUNDFONTS environment variable to point to the soundfont file. This post explains how to do it on Linux; it's the same environment variable on Windows but the process for setting an environment variable is different (you should be able to find instructions on that if you Google it, better than what I can explain on my phone).