2]- Type Compmgmt.msc and hit Enter. Computer Management console will open up.
3]- In the menu on the left select Disk Management under the storage tab. You will now see all of your drives/partitions in the right hand side panel.
4]- Right click the USB drive you want to assign a permanent letter to and select Change Drive Letter and Paths.
5]- Click on Change.
6]- Assign any drive letter you want and click OK
7]- It will give a warning-you can ignore it since there are hardly any programs that depend on USB drive letters. But at the end of the day its your call, whether to go for it or not.
8]- The final step is to select File > Save and save the file in the default directory. Close the Console and you are done.