Segments with custom ledmap

Hi! I have create custom ledmap for my setup and now I wont control matrix by segments, but cant do this.
I can add segmets, but when I am trying to change their dimensions nothing changes.
I am using latest moonmod beta.
Is this bug?

You can upload multiple ledmaps (ledmap[0-9].json) and specify which ledmap to use for each segment.

I cant see how can I do that. In segments there is only one comobox to select ledmap for whole preset.
Another way (I hope) is to select jmap in segments settings, but I cant find out how to do that either

Ledmaps as originally intended affect entire matrix. Not segments.