Change Cost Element planning layout OPO2

Hello,

We have a custom planning layout defined in our system and our client is asking for the changes in the layout.

I was able to change the descriptions and delete the old element definitions in transaction OPO2.

But I wasn't able or aware to add new characteristics(custom & standard) to the element and there is no such option to create, I can only see some standard characteristics in this screen.

Please help me with the steps or process to add new characteristics to the newly created elements.

Thanks,

Chaitanya