Custom bracketing

[Tru]

Hi everyone

I am quite new to QDSLRDASHBOARD and I was trying to set up a Custom bracketing with a shutter speed scale from 1/8000 to 2". (Picture1)
I do not understand why I can not change the under exposure EV step in order to achieve the desired scale from 1/8000 to 2.(Picture2)
Do you have any suggestions?

Any advice or thought is appreciated.
Thank you