Firstly, groups are not given immunity based on "levels", i.e., in your second screenshot, it
looks like regular and mod are above owner, but they're not. What's going on here is that you have an inheritance tree, where more than one group is inheriting from "user". Since you can't really display a tree in a list, it just starts up one branch of the tree, then continues on to the next.
Having an inheritance tree is very advanced behavior, and isn't recommended (unless you
really know what you're doing). You should ensure that each of your groups inherits from the group you want below it, such as:
owner -> coowner -> superadmin -> admin -> mod -> regular -> user.
Secondly, if you don't want lower groups targeting higher groups, you'll want to set up your
"Can Target" fields to be "!%group", where "group" should be replaced with the group above it, like so:
owner: *
coowner: !%owner
superadmin: !%coowner
etc..
This will set up your immunity values as you most likely would like them to be.
Thirdly, it's not really recommended to have groups above "superadmin".
Read this rant from Mr. President as to why setting this up this way can be misleading.
Hope this helps!