Meldas L3 Ladder edit

Hi everyone,

We have a knuth numturn 400 with meldas l3 control in it.

I want to edit the ladder circuit, but I can't find where the onboard edit can be enabled.
The reason is to make an X/Z switch for the handwheel, because it can be change just in the PLC-SW setup and it's very frustrating.
The switch is working (electronically), I can see the PLC signal in the diagnostic screen, the next step is to change the ladder, but it show a "not write" message.

I searched the whole internet (maybe not the whole, but big part of it :) ) and didn't find a solution.

I can program PLC ladders so it won't be a problem. I found the coils and devices, saved it via com port, downloaded the whole ladder circuit from the machine, I also wrote the necessary program part on paper. I have everything I need except this little thing... I can't edit the ladder.

If someone have any information about this, it would be very appreciated. (Mostly with words, but with really nice words :) ).
If not a complete solution, but some hints that may help, that would be good too.

Thank you