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STEP BY STEP
-Go to "ROSTER CREATOR"
-Go to "CREATE ROSTER"
-Click on one of the created rosters (any, let it load, it took a while for me)
-In that menu, you should see all of the roster editing options
-Back out of that menu having made the changes that you want, and click on "Create and Upload Roster" so that your changes will save (name it whatever you want)
-You can use those settings in a quick game by pressing "triangle" (PS4), and then selecting your roster (which for me is the last one on the list)
Now, any time you want to make changes, there should be an "EDIT ROSTER" option under "ROSTER CREATOR". Go there, and click on your upload and make the changes you want to make there. Any changes that you make from that menu should apply any time you play a quick game using your updated roster. Just be sure that before you start a game, you choose the roster that you uploaded.
Whenever you back out of "EDIT ROSTER" having made the changes that you want, click on "Create and Upload Roster" so that your changes will save.

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