While you can change the NAME of the user account what is not supported is changing the name of the home folder.
Try this. Create a new user account with the name you want to use.
Now use that account.
DO NOT REMOVE THE OLD USER until you have all you need working well and even then, keep it as a spare account.
Bob
My granddaughter Jenna "upgraded" me by giving me her "old" desktop PC when she upgraded to a new mac laptop.
Now everything --such as Jenna's documents" -- still shows up.
I love that girl, but I want my own identity.

Chowhound
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