In fact, I have more problems than the one described in the subject hehe
First, I cannot re-mount the system as a rw. I got an error related to the fstab. the only "weird" I did is to mount it through sshfs to copy some files there. I found a way in the forum to do it but I need to send a couple of commands and it is not so handy...
Second, I am connecting an external sound card via USB (like the "good one" it is recommended here). The card always have the same ID equal to 1. The problem is that each time I re-boot the PI I have to change the soundcard ID from 1 to 0 (and the other way around) because if not I can't hear no sound. The weird thing is that the IDs are always the same and sometimes it works selecting ID = 0 in the samplerbox.py although the alsamixer says that the Id card is 1.
Finally, I need to execute manually python samplerbox.py to make it work.
Hope someone has a solution