I am running Knoppix installed on HDD. I want to insert my USB drive, and use it to copy files and edit notes I need to print on another machine. I first had it working fine, but now something has changed. It mounts and lets me read, but I can no longer write to it, create a new file or folder, or edit anything on it.

Is there a simple way to permanently change permissions to allow write as well as read access? I am a beginner, so exact instructions or commands to issue would be perfect. TIA