ims20 song/pattern question

[felipe46n2]

hello people, I'm new to korg products, using the iMS20 on ipad2 and i'm curious if anyone knows how, while making new patterns and songs in the same session, how to keep the drums unique in each pattern? I'm running into a problem where after creating 5 or 6 patterns with different sounds, when I save the music, all previous patterns in that session now have the same drums. Frustrated!!!!

Second question: Is it possible to open previous session patterns into new songs I have created?

Any help would be appreciated! Thank you!