Open your /etc/fstab and locate the line that talks about your usb memory..it's got /dev/sdaX or sdeX or something, where X is a number. Alter the line and add to the options an option
umask=022 to let every user read/write it..so the line becomes like this (might be a bit different on your machine, so just add the umask):
Code:
/dev/sda1 /mnt/someplace auto defaults,umask=022 0 0
All the other options in the above line may vary on your machine, so don't alter anything else, just add the umask. If you want only yourself be able to read/write the memory, alter the mask.