Apple iTunes defaultly stores iTunes media on your Mac or Windows PC in the following storage locations:
Macintosh HD | Users | <User Account> | Music | iTunes | iTunes Media
C:\Users\<User Account>\Music\iTunes\iTunes Media
Normally, you should be able to change the default location of the iTunes Media folder by launching iTunes and then going to:
iTunes | Preferences | Advanced
Edit | Preferences | Advanced
Once you are in the Advanced Preferences window, you should see the current iTunes Media folder location and be able to change the location by clicking on “Change” and selecting the new location.
Recently, on a Windows 10 (version 1809) laptop running the latest version of iTunes (version 220.127.116.11), I experienced an issue where each time I tried to change the default iTunes Media folder location, iTunes would revert to the default location after quitting out of iTunes. The laptop recently underwent a reformat, clean installation of Windows 10 and was up-to-date on all current software updates and patches. In addition, iTunes was uninstalled, the laptop was rebooted, and iTunes was subsequently reinstalled as a precaution; however, the issue remained. I did research the issue but couldn’t find any current reports of known bugs/issues between Windows 10 (version 1809) and iTunes (version 18.104.22.168) like the issue at hand.
As a workaround, I decided to try creating a new iTunes library in the location where I wanted the iTunes Media folder to be located.
To do this, first close out of iTunes then do the following:
Hold down the Option key while launching iTunes
Hold down the Shift key while launching iTunes
An iTunes window should come up which says, “Choose iTunes Library.” You will need to create a new library in the location where you want the new iTunes Media folder to be located. Click “Create Library …” then follow the on-screen prompts to select or create a folder location where you want the new library to be located then click “Save.”
Once that’s done, iTunes should generate an “iTunes Library” database file in the new iTunes Media folder location that you selected along with sub-folders for “Album Artwork” and “iTunes Media.” If you go to either: iTunes | Preferences | Advanced on a Mac or Edit | Preferences | Advanced in Windows, you should be able to verify that the iTunes Media folder location is set to the new location which you previously selected. To be certain the change will not revert, close and re-open iTunes and verify the change again. Also, take a moment to check that your other iTunes settings are correct (ex: “Keep iTunes Media folder organized” and “Copy files to iTunes Media folder when adding to library” are selected, if so desired).
While there’s nothing wrong with using the default iTunes Media folder location, if you prefer to use a different location and run into similar issues changing the default folder location and/or iTunes retaining the change, creating a new iTunes Library is a potential workaround.