how to change zoom shortcut in sai2?

i was using sai and sai2 side by side (i liked brushes in 1 that i couldn't replicate in 2, but sometimes i need 2's larger memory) and it was fine, however, i just got a new pc and a fresh install of sai2, and i found that the scroll wheel zoom is inverted from sai 1. of course i went into the shortcut settings to change it, but it doesn't seem to see what i've done. no matter what i set 'page up' and 'page down' too, scrolling is always inverted zoom, and i can't find any other options that might be the scroll wheel. what am i doing wrong?