Fl studio midi sync problem...

So I have everything workin...its just that say when i record one track and then try to do another track. It will change up my first track if you know what i'm saying..cant get it to separate..

this is a pretty basic question just cant figure it out... gotta be something i'm missing..

can anybody help me out on this?

yeah thats what i did..i had one sound on track 3(1a) and then went to track 4 then change it to (2a) and the sounds on track 3 change up. is their something i should be changing in fl studio or something