just when I move something into the pendrive I getWhat errors you get when you try to copy the files? You can use the Terminal to Copy files using sudo as root permission, which should have full access. For example :
sudo cp -R /path/to/directory/ /path/to/destination/ #Copying Directory /Volumes contains the internal and external volumes. # Use cp --help or man cp to get help or read mannual.
it's like I do not have write permissions on any external device