How do I add my library to other users on my computer?

You can add full access permissions to your user's Music folder for the other user profiles on your computer, then when those are active they could use the shift-start-iTunes method to access your library. Note that iTunes isn't really set up for multiple users in Windows. If one user account has iTunes open and you use the fast user switching method to open a different account then you cannot open iTunes in the second account. Similarly the computer shares authorizations and associations with all user accounts which likely limits what features other users are going to have access to. See Authorization vs. association - Apple Community for more.

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