mass transport: how to change the unit of axis of chart?

Hi there,
in mass transport, how can I change the unit of the axes in the "local concentration history"-chart? I want to have [mg/l] and [d] and don't find a option to change them.

Thx!

found it:

tools --> units --> time [d] for x-axis
                    --> Concentration [mg/l] for y-axis