Problems connecting my external hard drive to a specific drive

This is my first thread post, and I'm not the most tech savvy, so please bear with me, your help would be very much appreciated! Let me just describe my situation: I have a lot of music in my itunes library, so much so that it doesn't fit on my computer alone, so I decided to buy an Iomega HDD 1 Tb external hard drive to store all the files. Since all the files are on the hard drive, I have to plug it in to access my music through itunes. This is because all files on itunes have a specific location where they are found at, and mine so happen to be on the Iomega HDD (G:) Drive. So normally, I just plug it into the same USB port, the G:\ Drive, and I'm fine. Recently however, I've noticed that every single time I plug the external hard drive in and turn it on now, it is in the F:\ drive! I've plugged it into every USB port on my computer and it always comes up on the F:\ drive! I just really need to know how I can make it connect to the G:\ drive, or else I can't access my files on itunes. Any suggestions or tips will help!

There is a complete guide given on how to use: IOMEGA HOMEMEDIA NETWORK HARD DRIVE USING YOUR ITUNES SERVER, download the pdf file from here. The tips that is given are as follows:

1. Click on the Iomega Home Storage Manager icon in the System Tray (Windows) or Menu Bar (Mac), then select your drive from the Configure submenu.

2. Enter the administrator password if you have created one, then click Log in. You will not see the password screen if you have not previously created an administrator password. By default, the administrator password is blank.

3. Click on the Folders button.

4. Click the iTunes button next