If you change information in your local browser, that does not change anything on the back end.
The User is logged in via an authentication token, I believe, so you can’t masquerade as anyone else to the back-end:
Because there is no fooling the server, you will not be able to make any change as another user.
As soon as you refresh the browser, your local changes will probably be wiped out. Worst case you will probably mess up the javascript app state and have to delete your cache.