When sitting, my legs go through the chair/bench! =0

Like the title says... any chair or bench, and my avatar's feet and legs stick through it!

I thought it was because my legs were too short, so I increased the size with no luck...

(See attached images)

What can I do to fix this problem? =[

Thanks.

If you're sitting on someone else's chair, there's probably nothing you can do about it. Try sitting on another part of the chair.
If you're making a chair, you need to add a "Sit Target".
The thing is, LL is atrociously lazy and innatentive to details, so there is no easy way in the UI to do something that is required everywhere. You need to do a script with llSitTarget... this requires some knowledge of geometry, or a lot of patience if you want to do it by trial and error. Some people have made tools to calculate Sit Targets... I think Rickard Roentgen had one.

But this is the only avatar I have that does this =[

Is it because I'm shorter than before?

Maybe. I don't know. I do know that there is nothing preventing your avatar from interpenetrating with objects when you are sitting on something. Before people knew about the sit hack we used to do something called "ride the magic prim", meaning, you would sit on a cube and then edit it, allowing you to move yourself through walls at will.

Maybe I'll make a cube with an invisible alpha texture then sit on and move it over the chair I want to sit on =D

Arg... no matter what I change on my body, it still won't work... maybe it's my pants?

(Please see attached images)

If you can help me out here anyone, it would be much appreciated

must be your size - however, why can't you make a small, flat prim to sit on?

Not that this is necessarily useful...