Based on the work-around listed here it states to uninstall and reinstall your game.
I downloaded the game on my wife's Laptop through her XBL account was able to switch to my XBL account without any issues after doing the following:
I located both folders for pso2 (one being the Mutable folder, the other being WindowsApps) and changed ownership to Users. You can achieve this by right-clicking on the parent folder, selecting properties----> Security Tab -----> Advanced. Click to change ownership and find Users, make it the owner, and select the box to apply it to all subfolders/items, then hit apply.
I did this for both folders PSO2 is located and it allows me to switch XBL accounts as much as I want, all I have to do is enter my password and authorize administrative privileges.