... assuming that OP is talking about latex export.
I assumed he was talking about the org buffer - we'll have to wait
and see who guessed correctly :-)

--
Nick

Subtle. Yes, both would be nice, both in the buffer and as an HTML export. I put this

(setq org-list-demote-modify-bullet

'(("+" . "-") ("-" . "+") ("*" . "+") ("-" . "8594")))

in my init file, but I'm not seeing it as a choice in customize.